Why Install An Aftermarket Exhaust?
Weight saving, increased power, looks, and sound are the main reasons people install aftermarket exhausts. See the Exhaust Theory section of the FAQ for a lengthy technical discussion of exhaust systems.
What Exhaust Systems Are Available?
Until the year 2000 there were only a handful of ready-made aftermarket exhausts available for the NSX. Since then the number has jumped very quickly, in part because a number of new systems from Japan are now being imported. Almost all NSX exhausts are cat-back systems, meaning they replace everything "downstream" of the catalytic converters (the pipes, muffler, and exhaust tips). Almost all are also made out of stainless steel, though a few offer titanium.
There is no "best" exhaust. What is best for a given person is determined by several factors, including subjective criteria such as look and sound. The key factors to keep in mind when comparing aftermarket exhausts are, in no particular order: 1) Increased HP 2) Weight 3) Sound 4) Looks 5) Price. You need to decide on your priority for each of these factors and then decide on the sound and look you prefer. Once you have decided that, you are ready to start deciding which exhaust system to buy. Do not judge an exhaust solely based on price. There are some excellent lower priced exhaust.
[MCA] Other comparatives: RM is "hand-made", DC/Comptech is also, RS-R is "factory" (rolled, machine-pressed seams vs hand welds). Comptech may be lighter, and seems to have a stronger warranty. No problems noted with RS-R to date, except under high cornering loads (track), which would've plagued most non-stock tip configurations, except maybe Supertrapp's plain ends. In the realm of the fixable -- RS-Rs come highly recommended. OTOH, I've listened to both Comptech and Randy's, they both sound great.
[BM] Mine has become a lot louder after putting about 30K miles on it. I have to have the window rolled up to hear the phone.
I love the sound. With the 4:56 gears VTEC comes up quickly and the roar is very satisfying. I honestly think it is louder inside the car because of the proximity to the airbox.... It definitely is throaty under acceleration.
[SA] I think someone on the list characterized the sound as like a Japanese motorcycle, except deeper -- that's not too far off. At idle, you hear the exhaust, not the sewing machine sound of the engine. There are no annoying harmonic resonances. At cruise speeds in the 3000 - 4000 RPM range -- it sounds great and turns heads on the interstate. Not too loud though. The sound is tight, deep and somewhat muffled. My friend commented that it sound like the car just wanted to go faster.
Backing off the throttle gives a nice rumble down but with no backfire crackling. At VTEC range, the sound changes significantly to much louder, with a higher frequency sound similar to an accelerating Japanese style motorcycle, but deeper. At 5500 and up, it screams.
When I first pulled away from the dealer with the exhaust, I thought -- gee nice, but I wish it was louder. I think the exhaust got louder after a couple hundred miles. Maybe some of the sound padding gets blown out or something happens that opens it up a bit more. After extended periods of driving hard (lots of full-out acceleration and speeds 80-160 mph), I did get a couple resonanating vibrations when pulling away in 1st gear -- but they went away quickly and haven't come back.
[WSC] I've owned both. I like the sound of the billet competition tip ALOT better than the resonant tips, not to mention I haven't blown out the competition muffler after two track events with the supercharger (went through 2 other mufflers already).
[DNG] I've heard a lot of CT exhaust rattle at the point where the exhaust tips connect. It's mostly with the billet tips. A lot of owners have tried to fix this, but was unsuccessful.
[SA] I blew out my CompTech exhaust in 6 weeks :-(. It now is louder and rattles at certain RPMs (very annoying). I talked to Bob at CompTech and he confirmed that when I bought my exhaust in mid September, that I received one of the last "Walker" exhausts. He said that they are now working with a company that is building an exhaust to their specification. He will ship me one next spring when I get my car out of hibernation. It would have been nice to get the good exhaust first. He said that the new exhaust will be quieter than the old one. I told him that the Walker exhaust was already too quiet when new. He suggested going with the billet tips on the new exhaust.
[SST] This is the newer second generation unit. It is by far the lightest and smallest of Comptech/RM/HKS. It is tucked up very high under the trunk, so much so that the muffler itself can’t be seen from behind the car. As far as the sound goes it is the unit I used I run the car with not Cat. The RM unit by the way made by B&B is far too loud without the cat. The Comptech exhaust sounds much like a large Japanese motorcycle with a after market exhaust (not as loud though), high pitched and tuff.
[DH - 99/1/8] Not sure which Comptech one I have now, but I can't blow it up, so I think they have it worked out. Also remember that my car is supercharged, and on the track at times it spits out flames through the exhaust, so my car will beat on the exhaust MUCH harder than a non-supercharged car. I don't think anyone had a problem with a non-supercharged car and a Comptech exhaust, but I could be wrong. When in doubt, I would call the manufacturer, as they are the only ones that can give you the exact scoop.
[BD - 99/1/11] I went through my local Acura dealer, Gary Force Acura, in Nashville and bought CompTech headers, exhaust and air flow. The exhaust "blew" this spring. Gary Force Acura called CompTech and they replaced the exhaust and I didn't pay any installation or shipping charges. I miss the sound of the blown exhaust. Talk about loud!!
[SA - 99/1/8] I bought an exhaust from CompTech in August of 1998. After six weeks of non-track driving (but spirited at times), it was exhibiting many signs of being blown. 1. It rattles at certain RPMs under load. 2. It rattles after high RPM acceleration. 3. It is louder.
I talked to CompTech and they acknowledge that I got one of the last "Walker Type" exhausts. They acknowedged that some people have experienced problems like the ones I was describing. They said that they had a "new type" of exhaust that was being developed to their specs and would be an improved exhaust. They agreed to cover my exhaust under the warranty program and replace it for free -- although I am paying reinstall costs. (Their warranty program does require that you ship the defective part to them and they determine if it has failed).
[SA - 99/3/11] I put a new CompTech billet tipped exhaust on my 91 NSX last night. Previously I had an older model CompTech resonated tip exhaust.
First off, the new billet tip exhaust is quite a bit larger than the old resonated tip one. In fact, the new resontated tip one is larger too (the wrong one was shipped first, so I got both kinds).
The pre-Aug-98 resonated tip exhaust weighed in at 27 lbs. The new billet tip exhaust weighs in at 45 lbs. The muffler portion is huge. It stretches the entire length between the rubber hangers. It must be at least a foot longer than the old one.
The installation went pretty well. I struggled with getting the old one off. The bolts came off with a bit of finesse and some cursing. The tough part was that I have CompTech headers too, and the newer CompTech headers use spring joints where the headers connect to the catalytic converters, hence the catalytic converters move around a lot while working on the exhaust making the job more difficult if you are doing it yourself.
The craftsmanship is once again superb. The welds are very neat and clean. The mounting holes lined up exactly with the catalytic mounting bolts.
The sound is a bit hard to judge because my car is still up on jacks in my garage. I fired it up and the sound is deeper, and has a more raspy aggresive tone than the resonated tip. I didn't thrash on the throttle too much being the engine was cold. Once the snow melts around here, I will take it on and see how it sounds under WOT (the fun part).
I started about 10:30pm and took my time. I was done at 2am. Man, was I exhausted! (sorry, couldn't help myself). The longest time was spent dealing with a bolt that stripped while using a 12 point socket. I converted to a six point socked and with care, got the bolt off.
If you are doing this work yourself, here are my tips.
Lastly, major kudos to Bob and Chris at CompTech for getting the parts out to me and being very cool about replacing my previous exhaust. They were very pleasant to work with.
[SA - 99/3/29] Review of new CompTech billet tip exhaust
We are having an early spring here in Minnesota, so I have my NSX back on the road. As some of you may recall, I installed a new CompTech billet tip exhaust this spring. I thought you might be interested in a review.
Everyone warned me that the billet tip was louder than the resonated tip. I think it is somewhat louder, but not a lot louder. (Its hard to compare because my previous exhaust was partially blown and was louder due to that). Maybe the billet tip exhaust will change as I break it in. On the interstates, cars hear me coming, and going. It is NOT too loud to drive around the neighborhood or leave the house at 5am.
The most notable effect is that the exhaust is deeper than the resonated tip, and it has a very cool tuned sound. There are two distinct tones that harmonize nicely as you accelerate. And of course, at VTEC range, it screams "I AM A SPORTS CAR GOING FAST!!"
I can hear the exhaust in the car at all speeds, yet it isn't intrusive. I can still carry on a conversation without talking louder and there is no problem listening to tunes.
The billet tip exhaust is much larger than my previous resonated tipped one. It weighs in at 45 lbs, compared to 27 for the resonated tip. But, the exhaust portion (the oval tube) is much larger. In fact, when I look at the CT web site, my exhaust looks just like the SuperCharger exhaust (hey, maybe CT wanted to make sure I wouldn't blow out another exhaust so that's what they gave me!!).
The billet tip cans are larger than the resonated tips. They are polished, with the CompTech name etched in the side. The insides are not finished and have a dull grey appearance. I used high-temp black flat paint and sprayed the inside of the cans. They look AWESOME this way. Plus, I won't be wiping out the inside of the cans everytime I wash the car like I did with the resonated tips (they have a polished interior).
That's it. I am happy with the exhaust!
[N] DC Sports Exhaust (New is about $1300): IMO the best looking exhaust but perhaps not the loudest. The 4" tips come way out the back and make your car look like an Indy car. You can also see the diffuser holes and they look very trick. I do not have the headers (yet) but did not notice the 8-10 HP promised by this system on their web page. The note itself is excellent, albeit more subdued then other options and if you don't care what your neighbors think of you, get the RM Exhaust system. I followed Mark Johnson around all weekend and could hardly hear my exhaust over his. The RM system has a better note than the Ferrari 355. I know because there was a 355 parked next to us and when the owner left, I was surprised how quite and subdued the note was (even though the car was hauling tail).
[SST] Same size as the stock exhaust. It sounds more like half way between the Comptech unit and the stock unit, but definitely sounds after market. It's tips look like the Comptech exhaust.
[WM] I like the sound because it is not too loud but still better than stock. I don't know if you can buy a new one anymore.
[DB] HKS made perhaps the first, or one of the first, aftermarket mufflers specifically designed for the NSX. It is purported to give a modest HP increase, maybe 5HP, but in my opinion it's too small to tell. The sound is *slightly* louder and throatier than stock. The design and build quality is second to none. It won't blow out or fail, at least not after a year under supercharger duty. It's not a lightweight muffler. It is a form-fit-and-function swap for the stock unit.
[CA] The sound is great, not raspy, just a full sound of engine, almost F1 like, except not as high pitched, but maybe it would be if we had the capability of 15000 rpm. The idle is nice and....rumbly, but not tinny sounding. The construction is awesome, even the meffler was polished, the welds were solid and very professional. I am very happy with yet another great RM product. Verdict....highly recommended.
[JF] for those of us seeking the perfect NSX exhaust note, here's my $.02 worth: Earlier this year I installed an after-market exhaust with resonated tips. After installation, I must admit, I was disappointed with the sound (or should I say lack of sound) of my new exhaust. The RM Exhaust, on the other hand sounds awsome from idle to 8 grand. The muffler also tucks up completely under the car except for the wicked dual DTM tips. In my opinion the RM Exhaust is how the NSX should sound all the way through the power band (not just at VTEC). Did I mention the DTM tips...cool
[CW] It's like going the the automobile veterinarian and getting your NSX de-neutered.
[AF] I had the RM / B&B exhaust installed this weekend and it is exactly what I wanted. If any of you want that sound of a Ferrari, I think this exhaust will do just that. The installation was pretty smooth aside from two bolts rusting up. Interesting note for those who care, we tried WD-40, liquid wrench and another lubricant and nothing worked except this stuff called "PB Blaster" "as seen on TV"purchased from NAPA. I though the guy was kidding, but this stuff safely eats the rust away so you can easily remove the bolt. Try it some time. Anyway back to the plug...this exhaust is incredible. It is loud, but note to loud. With the exhaust, the car attracts even more attention...if that is even possible. With the combination of air intake, the engine sounds incredible. For those of you out there with an exhaust, you can relate, for the rest of you, get one...it is worth the money.
[SST] This unit is the same size as the stock unit. It will give the lowest deepest sound. It will not sound like a import car anymore. Much like the cars used in 24 Hours of Daytona. The one thing I really did not like about this unit is that the tips are slip-on units that are then clamped on. The unit I have has the single oval tip.
A number of people have noted that at 3000-3200rpm (around where many people cruise at 70mph in 5th with stock 5-speed gears) there is an annoying sonic resonance freq that vibrates you/the car/anything free in the car. Some have even said that they have to drive 65mph or 75 mph but not in between.
[KP - 99/3/8] About an hour ago I finished replacing the RSR I purchased approximately 1 year ago with the DTM RM exhaust. I liked everything about the RSR except that it just wasn't loud enough. I'd been running it sans cats, and although it had a nice deep sound and a nice wail at WOT, it just wasn't LOUD! So, I decided to buy the RM and I call Randy on Wednesday to order it. Randy makes me a very reasonable deal on a used one that he had just sent back to his manufacturer for refinishing.
Before jumping into the install, I should add that a couple of other listers in socal have the RM. I like the sound of their cars and I like the DTM tips. However, the other reason is that I had previously purchased headers from Randy and have had the occasion to run through a couple of Canyonballs with him. He's a good businessman who is straight and honest. I'd recommend RM to anyone. OK, back to the story.
The RSR took about 20 minutes to drop out. Most of the time was spent getting the car on some jack stands. I put the RSR side by side on the floor with the RM. Hands down, the RSR looks better off the car and especially the canister. The RM's no slouch in the quality dept, however, but the workmanship on the RSR is pure perfection. Regarding weight, the RM is MUCH lighter. I got out the bathroom scale and got my 7 year old son to do some comparison tests for me. (You see, my bathroom scale has an abnormally low top-end which precludes me standing on it with anything heavier than about three feathers, so I have to enlist my son.) The RSR clocks in at a porky 44lbs. As I recall, the RSR was almost identical in weight to the stock exhaust. The RM weighed in at about 31lbs with the tips. A 13lb weight savings!
I was a little disappointed in the install of the RM. It didn't fit as nicely as the RSR and I had to grunt around at it and shout a few obscenities before I could get all of the bolts to line up. Now, I've still got the cat by-pass pipes in and I refused to loosen up the other end of these guys which would have permitted more play for the alignment. Anyway, with a little more grunting and shouting than I preferred, I got everything buttoned up. I have the same view of the DTM tips as other list members have mentioned. You have a tendency to try and angle them up to conform more to angle of the bottom of the bumper. However, you have to be careful because they will make contact with the bottom-most edge of the bumper at approx 3" back of the upward bend in the tips. If either the bumper or tips were constructed a little differently in this area, you could probably increase the angle upward which would probably be more aesthetically pleasing. Anyway, I basically have installed them according to Randy's suggestion and I left about 1/8" clearance at the bottom of the bumper to avoid any melting. They look good.
Ohhhhhh, but the sound! The RM (especially w/o cats) is very deep and very loud. Way cool. Oddly, the RSR would almost get linearly louder with RPM (under power), but the RM seems to stay deep but doesn't get a lot louder (a good thing) with speed. In fact, I'd almost say that in VTEC at WOT, the RSR sound was almost better but lacking the volume which, IMO, was needed. But, hands down, the RM is great for street driving where (if?) you want your NSX to sound authoritative. "I am NSX." "I have arrived at stoplight." "I'm ready to kick some ass." "Yes, I know that you read that I came with a nice, well tempered, 3.0L, 6 cyl, but I am very mad today, growling, and ready to kick ass and take names." "Grrrrrrrrrr." I love it!
[KP - 99/3/8] About an hour ago I finished replacing the RSR I purchased approximately 1 year ago with the DTM RM exhaust.The build quality of the RSR is awesome. Second to none. The detail work, especially in the welds, is spectacular. The entire unit is completely polished to a mirror-like finish and it just looks great. When I first installed it one year ago, I remember how easy it lined up with everything just like it was made by Honda. Lying on the shop floor after 1 year of usage (maybe 6,000 miles) it still looks brand new. The SS has turned a little brown especially at the bends but overall, it still looks great. The polished "can" is the same as it was new.
I liked everything about the RSR except that it just wasn't loud enough. I'd been running it sans cats, and although it had a nice deep sound and a nice wail at WOT, it just wasn't LOUD!
[MCA] Info on RS-R... seems both Car Trenz and Pit Crew offer competitive pricing. Am ordering this myself.
[MK, AV] The RS-R muffler is a high quality stainless MADE IN JAPAN with amazingly COOL exhaust note. It has good looking 4 tips and you have to see the product to appreciate the quality. Several SoCal members have this mufflers and I am one of the happy RS-R user. All of the RS-R users agreed that this is the most bang for the buck type of deal and enjoy 348 type of sound. RS-R mufflers @ $750 out the door. If you are interested, call Pit Crew at (626) 573-1837 or your after-market stores.
[DNG] Car Trenz has them for $850. (301) 762-5558 - Ask for Charlie and tell them Dave sent ya.
[TS] Good quality, good sound, good looks, $850 installed. What a deal !!
[KH] My friend Mike and I just bought 2 RS*R exhausts, which arrived Friday afternoon. We just finished installing them on our 92' and 93 NSXs, so I thought I'd drop this note about them.
First of all, We ordered the exhausts from Auto Fun Center (http://www.autocenter.org/
) from Brian at $850 each including shipping. I
Anyway, after installing them both we notice some similarities. The RS*R has dual 2.5" tips on both sides. On both of our exhausts the outer tips on the right side are both slightly lower (<1/8") than the rest of the tips. RS*R must be welding them this way (?). The tips on the right side of mine are slighty lower (1/4") than the tips on the left. The tips on Mike's NSX are even horizontally. The exhausts fit perfectly to our cars with no adjustments, banging, swearing etc. The exhaust looks very good and is very shiny (for now), you can see it glimmering through the rear black valence panel. Definitely a better look than stock.
The sound of the exhaust is a low throaty sound, not much louder if any. In VTEC it gets louder, but you can still have a conversation in the car with the windows up. I cannot hear the exhaust with my windows up at highway speed, although people behind me can. This is the sound I wanted so I am happy with it. I've heard it will get louder as it gets broken in.
[KP - 99/11/12] I bought my RSR from Pit Crew. Oddly, they had it in stock so I can't really comment on the promptness of shipping. They did have a good price too (about $800 with tax) but that was 2 years ago.
[AV] All of these exhausts, in my opinion, are big improvements in sound over stock. I have friends who have these different exhausts and have not noticed any droning whatsoever at cruising speed even with the louder exhausts (unless, of course, you punch the gas pedal). Personally, I have the RS-R exhaust and I am very happy with it. Looks great and sounds great. Very, very well made, too. At the same time it is the least expensive of this group. Why, I don't really know. Most of these exhausts cost between 1100 to 1500 bucks, depending on where you get it, while the RS-R cost me about 800 bucks out the door, installed.
"Stromung, the German word for flow. For us it means exhaust flow. The sound dampening is achieved by all welded Stromung racing mufflers. Each muffler is hand made and utilizes Stromung technology to more efficiently manage your car's exhaust flow and also creates the distinctive Stromung sound. The tube bending process we use is called mandrel bending. This process bends the exhaust tubing without crushing or reducing the inside diameter. The result is smoother flowing exhaust. The materials in building our exhaust systems are highly non-corrosive, aluminized, 16-gauge steel, which combined with all welded construction, gives our exhaust systems an aggressive, unique appearance. Stromung exhaust systems are designed to please the most demanding street racer, as well as the refined sports car enthusiast."
Comptech used to produce an NSX exhaust based on the SuperTrapp mufflers, but they were discontinued in the mid 1990s. You can still buy the SuperTrapp muffler and have an exhaust shop bend the pipes to fit it to an NSX if you want one, but it is hard to find a shop that will do it in stainless steel like old old Comptech units. Adjusted to "full loudness" this system has been measured at the track at over 108db with the cats in place. With the cats removed is is considerably louder to the point where your neighbors will curse you, pets and small children will flee in terror, and anyone with the misfortune to be behind the car when you floor the throttle may bleed from their ears. SuperTrapp - www.supertrapp.com - is located in Cleveland (phone # 216-265-8400). You can purchase SuperTrapp mufflers from many domestic car performance shops including Summit Racing Equipment - www.summitracing.com - (phone #330-630-0200).
Long the sound Ferrari owners UPGRADE to, Tubi exhausts are first rate quality, light weight,
[gary yates - 2002/02/06] Well, I finally got it in this past weekend, just now able to post. First, if your car has spent time outside, i.e. has been a daily driver or seen rain, bring out some sort of penetrating spray, or you will strip a couple of nuts as I did. It took multiple applications of spray, heating twice with a torch, and finally using an adjustable plier held tight with a Vise-grip to loosen the last nut. The old muffler comes off the hanging hooks fairly easily, but would have also been easier with some WD-40 sprayed on the body hooks first.
Lubed the body hooks and all bolts with chassis grease (could not find my loctite until the next day, and I wanted to hear this thing before weekend was over, dang-it), and the Tubi went on like a dream. Had to wiggle and tighten one of the three bolts on the rear pipe first to get the other two to seat properly. Mine did have gaskets that were still in the connection pipe pieces, just crush washer type gaskets. They looked good, so I reused them. I am having the same fitment with the plastic issues, but just on the right side, the left is perfect. The tips are either not level, or the fascia curves upward laterally?? I will have to bend the hangers, and have not done that yet.
As far as the sound. It is fabulous. I crank the car just to hear it. Nice low rumble on cranking, gets louder with just a little increase in pitch as RPM's rise, then pitch rises above v-tec. Never too loud in my opinion unless you are lugging arourn 2500 rpm in 4th or 5th, but I also have a K&N, so I may be having additive effects. It has been nasty weather here since Sunday, so I have not been able to drive much with the windows down, and definiteley not with the top off!
[tino stramotas - 2002/01/31] Four of the buyers have now installed it (I guess they can't wait) and reported back. I am real happy it worked out and I'm trying to get Tubi to lower their prices to keep the GB price going in the future, or at least something close. As a side note, I took my 360 back home from its one-year service at the dealership and drove thru the LAX tunnel late that same night. Second gear, 8500 rpm, third gear, the car sounds awesome with the secondary exhaust valves disconnected, then of course, I couldn't help but go out much later that night with my NSX and went thru the tunnel twice. You know what ? it sounds BETTER than my 360. The only problem with the Tubi is that it took a couple of months for it to really sound good. No regrets at all.
[larry bastanza 2002/02/01] I got my Tubi on Tuesday and installed it Wednesday evening. Pretty straight forward, it's a goods idea to have two exhaust gaskets handy. The part number for the gaskets is 18393-SH3-S00. Also depending on the age of your car, get 6 14mm exhaust nuts. They get smaller with age. In addition you will need to swap the exhaust hangers(rubber ones/4) from the original exhaust to the Tubi. A good trick to make this step easy is to give the two holes in each one a blast of WD40. It makes them slip back onto the body hooks easily.
One little fitment issue I had was that the tips actually touched the rear valance when I initially installed it.
Do this easy "adjustment", just push UP on the rear hanger rods evenly to lower the tips. I needed about 1/2 inch total adjustment, very easy. I have only been able to rev it a few times in the garage, since the weather in the east has gone to hell quickly, but.....Saturday is supposed to be nice. Time for a Tubi break-in drive
[NSXY 2002/02/04] Last Tuesday my Tubi arrived and Saturday my 19 year old son and I installed it in my 95 NSX-T. I have overhauled English and German engines, so I have some previous mechanical experience, but not with the NSX exhaust. My unsolicted observations and review regarding installation, fitment and function are as follows: I rented a clean professional auto repair bay at a local exotics-only car dealer, which included a nice lift. My car has only ~10,700 miles and is like new, even underneath, so removal of the OEM exhaust was expected to be easy, and it was. We used WD-40 (not Liquid Wrench) for rusted nut/bolt penetration, and the 6 nuts came right off, first try. We used spray silicone to pre-treat the 4 rubber hangers, and it worked fine to make the hangers more pliable. We lowered the OEM exhaust with no problem. The fitting between the OEM exhaust tubes & cats had no gasket.
We cleaned the rubber hangers, reapplied silicone and mounted them on the Tubi stainless steel hanger arms. We lifted the Tubi, hooked the hangers to the subframe hooks and bolted the pipes to the cats w/ ~25 lbs of torque, no problems.
However, the dual tips on both sides nearly touched the underside of the black plastic valance, which we expected from other reports in this thread. Also, the right side tips were evenly spaced within thier alotted space between the verticle portions of the valance, but the left side tips were not centered within their space. We then tried to adjust these various positions of the tips by silicone-treating and manipulating the hanging positons of the entire suspended exhaust system, including the cats, but this had no permanent effect on the verticle or horizontal tip placements.
We then tried to bend the rear hanger arms of the Tubi exhaust upward, as recommended above in this thread, but this was impossible with the exhaust installed, because the Tubi hanger rods are thick and stiff stainless steel that is very difficult to bend, especially with limited access while installed. So we completely removed the exhaust and placed it on a blanket on the concrete floor.
Using a flat-edged, 2.5 ft long pry bar, we repeatedly applied leverage to the stainlees hanger rods, using the attached exhaust tube as a fulcrum, and using a steel ruler to measure the distance of each hanger to the floor. We did this until both hangers were adjusted upward ~3/8" higher than their original placements. We then reinstalled the exhaust. The exhaust tips were then properly positioned about 1/2" below the valance. However, the horizontal positions of the tips were unchanged, with the right side tips centered and the left side off center, and that's the way it remains. The only way I can imagine to fix this would be to heat and bend the left side exhaust pipe, so I'll just leave it for now. Fitment issues on these first 10 exhausts (from this group buy) will hopefully be solved with Tino's feedback, by the time Tubi produces another batch.
We then started up the car for the first sound tests, and $HIT!!!!!!... what an experience it was in that mainly closed bay: Booming sound that at first seemed way louder than the RM exhaust with which I'm familiar on a local 94 NSX. We quickly realized that it may be because we were inside a bay and not outside on the road, so we delayed judgement.
While on the lift, we checked for exhaust leaks and found that the right side tube connection to the cat had two leaks, so we decided to use a black sealant compound for exhausts. We loosened all 6 nuts (both sides), liberally smeared the sticky black tar-like compound all over the ends of both the Tubi and OEM cat fitting surfaces, and we reassmbled everything again. A quick start up and tests showed the leaks to be gone! Finally, it was time for a test drive!
As I backed the car out on to the lot, and every conversation on the car lot stopped, and all heads turned my way! Everyone, customers, salesmen, kids were watching this unusual red exotic back out of the bay. As I drove across the lot and turned onto the street no one said a word - talking would interrupt what they all needed to do: listen to this amazing car get it on!
I first drove around with my son, then had him take it out so I could listen from afar, and I am very pleased with the Tubi sound. Taking it through the gears is great. It's got a moderate amount of low rumbling tone up to about 3K rpm, but then gets more refined through the mid-rpms, then screams at higher rpms. It may actually be louder than the RM, but that measurement can only come from side-by-side testing. I have not yet been able to hear from my exhaust the higher pitched secondary "schrill-type" sound that Tino's car produces at higher rpms, as captured by a posting by akira3d of a video/audio recording on a different thread http://www.nsxprime.com/ubb/Forum1/HTML/002750-2.html. But this may eventually come from an exhaust aging process, as Tino describes.
I am quite certain and would put money on the feeling that my car has more horsepower now. It's definitely faster, and no, it's not just my hearing. Some people have scoffed at the notion that an exhaust alone could give such an increase, but Comptech has shown on the dynomometer that its exhaust alone, WITHOUT other mods, does give 8 more rwhp. See http://www.comptechusa.com/images/dyno/2000NSXscPlot3.pdf I'd guess the Tubi gives at least the same rwhp increase as the Comptech exhaust.
On Sunday my wife and I went out driving the local hills, and although she is not a "car buff" at all, she liked the sound too, and did not find the increased decibel level objectionable. The increased sound is so fine that I can predict with certainty that my gasoline bill will be going up, because I'm now constantly wanting to go for a drive!
Final Observation: NSXers know that the mere physical appearance the NSX is sufficient to turn heads and produce lots of gazes from onlookers, unless it's a pitch black night of fog, and no one can see. If you add the Tubi exhaust to your NSX, you will have absolutely no possibility of being inconspicuous in the light or dark, so forget it, if you're shy and don't want to be noticed! For my experience, the OEM stealth is gone! It is true that the NSX should have produced this type of sports car sound from the beginning, and this is another area where Acura engineers and/or marketing people need to get a grip for future development.
Thanks much for your help Tino. (BTW, a 308 owner at the shop asked me where to get one for his car).
[BSD] Exhaust systems are meant to be able to move under the car. If you think about it, the engine is on rubber mounts which allow it to pivot. Plus, the exhaust system flexes with temperature. Also, bumps and other forces cause it to move about under the car. If your cat (or any other part of the exhaust) is 1mm from the body, it *will* hit. It should be farther than that from the body.
When you modify your exhaust, even as simple as replacing headers or mufflers, you can really change the location of things. Exhaust systems are not perfectly aligned, nor can they be expected to be. The heat causes them to torque in various directions. This is why there are so many muffler shops that can make custom exhaust systems... because they all need to be bent here and moved there. I think the normal process of installing, say, a new muffler is:
Sometimes, this takes cutting, bending and welding.
Does Removing Or Bypassing The Catalytic Converter Help?
[BCH] Removing the cats on an NSX yields no practical performance benefits. I configured my Supertrapp muffler as a straight through with no silencer disks and the torque was miserable below 6000 rpm, less than stock, which proves that messing with the muffler alone will give you all the back pressure reduction that is beneficial.
[LL] For the record the weight savings running test pipes is 17#, they are not as heavy as you would think. According to Comptech the HP gain is 5-6 and the sound increase is 2 decibels. I strongly challenge those that claim a performance degredation. It's more likely they also installed an exhaust system and that system is responsible for the low rpm hp drop, thats pretty common. I *have* personally seen perf degredation from cat removal on other vehicles, but I've had mine off and on a few times and notice absolutely no degredation. The 2 db is noticably louder, but just a bit. The negative is that exhaust resonance vibrations are present sans cats. The severity varies with the particular exhaust. If you want a pure exhaust note, leave-em on, if you want HP, take them off. I'm personally hoping to settle on an exhaust system that cancels the vibes out. Stock systems and HKS units drown them down considerably, Comptechs new unit and their supertrapp are both bothersome sans cats.