Review of Angus (Wil's) AP-X exhaust

[996garage]

After recently purchasing an 03' Silverstone, I knew that I would eventually put on an aftermarket exhaust, since I had done so with my last 7 sports cars. I initially went the "safe" route and purchased a Comptech exhaust.

Upon driving the car home from the install shop (es motorsports in Gardena, CA), I could hear a little added growl that the Comptech provided, and I immediately knew that I wanted more! However I did not want anything that was "wake up your neighbors" loud. I've heard some of the Taitec and GT-One style exhausts, and they were just a bit too loud for my personal taste. Just a few days later I started speaking with Wil about his AP-X exhaust, and ended up purchasing it.

I have never wrenched "underneath" any of my vehicles in the past, but Wil explained how easy it was to install his AP-X exhaust due to its modular design. Since I had a jack and jack stands, I figured I would give it a try and document the process with photos for you to see.

I took my time with the install, and the whole process took me 2-3hrs working alone. Jacking up the car and removing the Comptech exhaust took me about an hour, due to one hard to reach bolt and a stuck rubber hanger. If I had just sprayed the hanger with WD-40, the hangers would have come off easier.

Upon opening the box, I was immediately impressed with the high quality of the exhaust system. My wife commented that she hasn't seen me so excited before. I'll let the photos speak for themselves...

install photos next...

 

[996garage]

I had to remove the adapter pipes from the Comptech and swap them onto the AP-X exhaust, so that took an extra 45min. Per Wil's recommendation, I sealed the adapter pipes to the exhaust using Permatex Copper gasket maker.

There's only 4 spring loaded screws holding the exhaust to the cats, but one of them is a little tough to reach.

(Y-pipe clamp design makes assembly easier)

(attached 2nd muffler)

Since the AP-X exhaust consists of 4 separate pieces, it allows for more adjustment points, which is a nice feature. The only tough part is tightening the two muffler clamps down hard enough so that they can't move. If you have a compressor with impact gun, this is no problem, but I didn't.

Overall it was a simple install, and I'm extremely happy with how it came out. I like how the shiny exhaust mufflers show through the rear valance mesh. I'll post the initial startup video next...

 

[996garage]

Sound impressions:
Upon initial startup, I was pleased by the louder growl. After driving with this exhaust for a week now, I would compare it somewhat to a stock Nissan 350Z exhaust sound, except a little bit louder. It doesn't have the identical sound pitch of the Z, but the sound volume and tone is the closest thing that I can think of.

When under wide open throttle, the exhaust growls nicely at a loud, but not obnoxiously loud level. Under WOT, the volume stays constant at a nice loud level, but it does not scream like some others. I especially like the fact that when under light throttle, you can't even tell that you have an aftermarket exhaust on the car.

The only thing I noticed is that there is a hint of drone between 2000rpm and 2500rpm.

In my neighborhood here in a suburb of Los Angeles, the cops are very strict. I have been pulled over for loud exhaust on several occasions in other cars, but I don't feel I have too worry about tickets with this exhaust because it's not loud under light throttle. I love the sound clips of this AP-X exhaust with test pipes, but my neighborhood also has random emissions test check points which I have been pulled over for. (fortunately when in my wife's stock Audi)

Overall I feel that this exhaust is the pefect sound and volume level for someone wanting a louder modified exhaust sound, but not one that is loud all the time or one that screams. Please note that my car is 100% stock with OEM cats, so anyone running test pipes or an intake will likely have a different sound experience. Thank you again to Wil for providing me a great high quality product!

I typically attend the SoCal monthly meet, so if you're interested you can hear the AP-X exhaust there.

I will post videos as soon as I can.

 

[Hapa88]

Excellent review and great pictures. Thanks for taking the time to post this! Can't wait to hear it in person.

 

[PhAnToM]

Great review! Thanks for this write up and review.

I've always wondered how people with exhausts hold up here in Southern Cali where local law enforcements are so strict.

 

[RYU]

Thanks for the detailed review. How does it sound during fwy cruising speeds? Quiet enough to hold a decent cellphone conversation? This is one of the reasons I have kept my HKS for so long. Sometimes I need a car I can live with day-to-day even though I don't drive it day-to-day.

Also, on this pic, is it just me or does the passenger tip seem just a tad bit higher (misaligned)? I wonder if that's something that can adjusted. Perhaps it's just an optical illusion. Did you need to do much adjustment to get them aligned?

Definitely a nice exhaust

 

[Rusted_nailz]

I have the same exhaust and its sounds great. You can adjust it since the muffler section is a slip on design. I have test pipes on mine so its a little louder. No drone though. I have a few video clips in my thread.
http://www.nsxprime.com/forums/showthread.php?t=135412

 

[996garage]

Thanks for the comments. The exhaust is definitely very livable for daily driving use, however as I mentioned, it does have a little drone between 2000-2500rpm.

I think I might be the first 2002+ stock nsx running this exhaust...Wil mentioned that there was never any drone in the other nsx's that have been using the AP-X, but most of them are either NA1 or are running test pipes.

If you typically cruise on the hwy at that rpm range, then it might potentially bother you. For me it's not a problem as I'm usually just above that range. My commute to work is 32miles each way (fortunately opposite traffic) and I never have an issue with any excessive noise. I generally only notice it when I first engage a gear at low rpm. My nsx cabin is still much quieter than my beater supra, and no problems having cell phone conversations.

I took the photos right after I installed the exhaust, so I may have mis-aligned them just a tad. It is super easy to adjust, and I have re-adjusted them again since that time. As you can tell in one of the photos, all you have to do is rotate the muffer assembly up or down, and then re-tighten down the clamp. Due to its multi-piece design, this exhaust probably gives you more points of adjustment than any other exhaust out on the market. The long hangers also give allow you to shift the mounting point just a bit.

 

[Osiris_x11]

neat'o. . .

Nice exhaust, looks to be quality. In-particular, I like the large diameter rolled-end exhaust tips (w/ internal-resonator?).

I look fwd to hearing audio clips as well seeing vid' clips. Any plans to do a pair of dyno pulls (before/after)? What does the butt-dyno say?

Per Wil's recommendation, I sealed the adapter pipes to the exhaust using Permatex Copper gasket maker.

I'm curious about this "Permatex Copper gasket maker", would it be suggested to be used when connecting the OEM/stock cats' to an after-market exhaust (both are 3-bolt flange ends)?

There is an OEM/stock triangular gasket (for '91-'96) NSX'es, and they're generally recommended to be replaced when swapping exhausts (OEM to after-market). I was wondering if this "Permatex Copper gasket maker" can be used instead or in-addition to the exhaust OEM/stock gaskets (as the adapter-pipes <-> exhaust in the pics above are also 3-bolt flange ends).

There is a machined-recess in the OEM/stock cats' to accommodate this steel-ringed gasket. Is that also true w/ the adapter-pipes (or that's why this "Permatex Copper gasket maker" is needed)?

Reference:

P/N: 18393-SH3-S00
GASKET, PRE CHAMBER (52.5MM-53.5MM)

 

[angus]

Re: neat'o. . .

Nice exhaust, looks to be quality. In-particular, I like the large diameter rolled-end exhaust tips (w/ internal-resonator?).

I look fwd to hearing audio clips as well seeing vid' clips. Any plans to do a pair of dyno pulls (before/after)? What does the butt-dyno say?


I'm curious about this "Permatex Copper gasket maker", would it be suggested to be used when connecting the OEM/stock cats' to an after-market exhaust (both are 3-bolt flange ends)?

There is an OEM/stock triangular gasket (for '91-'96) NSX'es, and they're generally recommended to be replaced when swapping exhausts (OEM to after-market). I was wondering if this "Permatex Copper gasket maker" can be used instead or in-addition to the exhaust OEM/stock gaskets (as the adapter-pipes <-> exhaust in the pics above are also 3-bolt flange ends).

There is a machined-recess in the OEM/stock cats' to accommodate this steel-ringed gasket. Is that also true w/ the adapter-pipes (or that's why this "Permatex Copper gasket maker" is needed)?

Reference:

P/N: 18393-SH3-S00
GASKET, PRE CHAMBER (52.5MM-53.5MM)

The aftermarket adapter pipes are not machined for the o-rings. I like the copper RTV as it had never failed me yet!

Also: the tips are double walled but not resonated , this allows the outer polished finish to retain it's color due to the heat dissipation provided by the air gap, it also prevents the "megaphone effect of a 4" single walled tip - and it looks cool!

 

[angus]

I had to remove the adapter pipes from the Comptech and swap them onto the AP-X exhaust, so that took an extra 45min. Per Wil's recommendation, I sealed the adapter pipes to the exhaust using Permatex Copper gasket maker.

There's only 4 spring loaded screws holding the exhaust to the cats, but one of them is a little tough to reach.

(Y-pipe clamp design makes assembly easier)

(attached 2nd muffler)

Since the AP-X exhaust consists of 4 separate pieces, it allows for more adjustment points, which is a nice feature. The only tough part is tightening the two muffler clamps down hard enough so that they can't move. If you have a compressor with impact gun, this is no problem, but I didn't.

Overall it was a simple install, and I'm extremely happy with how it came out. I like how the shiny exhaust mufflers show through the rear valance mesh. I'll post the initial startup video next...

Steve, this was a GREAT write up, great pics and I am glad you like the system!

Thanks!

 

[angus]

I also can't wait to hear the sound clips on the otherwise stock '02-up car! I am thinking that the drone may also subside once the mufflers burn in (no matter how subtle it really is!) as this has not been noted yet on other cars.

 

[yoojeankim]

i recall people having drone with a new system when they actually kept there stock cats on but once they got test pipes or HFCs it was gone.

 

[996garage]

Here is a video I just took this morning prior to driving it. (you'll notice all the carbon dust and water vapor) I did a couple revs at 3K rpm and then a couple more at around 5K rpm.

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I only used the permatex to join the adapter pipes to the exhaust. It is a purely flat surface on the flange joining these two pieces.

I did not use any permatex to join the adapter pipes to the stock cats, because the cats had rounded convex ends and the adapter pipes had rounded concave openings held together with spring bolts. It did not appear that it was designed to use any gasket or permatex here.

I don't plan on doing any dyno pulls with the nsx. The hp gain is pretty small, so it's hard to tell of the improvements. The exhaust is just about the sound enjoyment for me. I've been spoiled having high HP cars prior to the nsx, so I would only dyno after big changes. (Porsche 996TT, SupraTT, 300ZXTT) I do enjoy driving the nsx just as much if not more than my prior cars.

 

[MetalSpikeRacing]

Amazing craftmanship!!!

Love it.

-MSR

 

[Mac Attack]

Awesome sound, quality, and price - IMO, this is the nicest exhaust out there for our cars!

If you have a resonance around 2000-2500RPM's and others with a similar setup (OEM headers and cats) don't, the only thing I can think of (I hate to say this) would be a difference in how it's hung. Did you accidentally leave off a hanger? Are all of them equally supporting the weight? Is this the newest car to have the AP-X installed on (read below, maybe your muffler rubber hangers are a lot newer and stiffer than other older models)....


I did some sound analyzing on my car with a custom exhaust to get rid of the 2000-2500RPM resonance here:
http://www.nsxprime.com/forums/showthread.php?t=134710

I wouldn't resort to anything like what I did on your nice exhaust - try shifting the mufflers around a bit instead since it's a coupling between the engine firing rate frequencies at that RPM range and the natural frequency of our cars. Maybe different hangers would isolate it better and eliminate the resonance for you.

Dave

 

[Osiris_x11]

pleasantly surprised...

The aftermarket adapter pipes are not machined for the o-rings. I like the copper RTV as it had never failed me yet!

Ahhh' makes sense, gotcha... thanks! I'm gonna grab a tube of that stuff for other applications, regardless.

Also: the tips are double walled but not resonated , this allows the outer polished finish to retain it's color due to the heat dissipation provided by the air gap, it also prevents the "megaphone effect of a 4" single walled tip - and it looks cool!

Neat tips, as I said before. I'm gonna look into such...

Here is a video I just took this morning prior to driving it. (you'll notice all the carbon dust and water vapor) I did a couple revs at 3K rpm and then a couple more at around 5K rpm.

Admittedly, it sounded totally different than I had anticipated. Without knowing what muffler-canisters were used, I assumed it'd be deep beefy/gurgle-like muscle tone (ie. Flowmaster, Magnaflow, etc'). Instead, it's got a nice pitch & quite a refined overall sound...

I only used the permatex to join the adapter pipes to the exhaust. It is a purely flat surface on the flange joining these two pieces.

I did not use any permatex to join the adapter pipes to the stock cats, because the cats had rounded convex ends and the adapter pipes had rounded concave openings held together with spring bolts. It did not appear that it was designed to use any gasket or permatex here.

Yups, I wasn't aware or not whether the after-market adapter pipes had a recessed surface to accommodate the OEM/stock 3-bolt flange gasket).

I don't plan on doing any dyno pulls with the nsx. The hp gain is pretty small, so it's hard to tell of the improvements.

Well, my curiosity was based on the as-shown pipe diameter(s) of this exhaust, as they appear to be noticeably wider (thus freer flowing?) than the other latest/greatest JDM pretzel'styleee NSX exhausts, and even other past popular NSX exhausts.

 

[996garage]

Mac Attack, Thanks for the tips on trying to move how the exhaust sits on the hangers...I'll definitely give it a try. (I'm sure I didn't miss a hanger) There was one other nsx'r that had indicated that he also had a little drone as well:

(listed on this thread in post #165)
http://www.nsxprime.com/forums/showthread.php?t=125042&page=7

 

[angus]

I have determined that the drone from this exhaust (A) does not happen at an RPM that many people would cruise at and (b) is only about half as loud as some of the other systems I have experienced , all in all I think this system is tame enough that it can easily be driven on a daily basis and still has just enough sound to make the car how it should have been frm the factory! (that is until you add test pipes!)

 

[996garage]

I would agree that the drone at 2000-2500rpm is very minimal, and that it is only 1/2 as loud as the drone I have experienced in some other cars with modified exhausts. I only mention it as I wanted to be thorough in my review.

Osiris, I'm not a big fan of the Magnaflow, Sebring, loud Mustang sounding exhausts, but that just my personal preference. This AP-X exhaust definitely has more of a refined sound which I enjoy.

 

[HIJACKER]

Thanks for the comments. The exhaust is definitely very livable for daily driving use, however as I mentioned, it does have a little drone between 2000-2500rpm.

I think I might be the first 2002+ stock nsx running this exhaust...Wil mentioned that there was never any drone in the other nsx's that have been using the AP-X, but most of them are either NA1 or are running test pipes.

I have a 2004, only other mod related to the engine is an intake. Otherwise, we're in the same boat. I posted a couple sound clips several months ago when I first got this exhaust. I agree with your review entirely. The drone is noticeable to me but I really don't mind it. Then again, I find myself in 4th/5th gear on most of the 35-40mph roads around the Northern VA area.

 

[Mac Attack]

If you have a 5-speed with the OEM final drive, then you are at 2000-2500 RPM from 40-55 MPH in 5th gear.

If the car is driven a lot around town, then I would expect a significant amount of time spent in the droning region.

That's why I sent out to eliminate this drone in one of the links I posted earlier. That concept would work here too if it were tee'd into the crossover connection so you wouldn't have to have two resonance chambers (one for the front bank and one for the rear). It shouldn't change the performance and the sound of this exhaust (except getting rid of the specific 105Hz frequency).

Might be something to consider (especially on a daily driver). It sure is a nice-sounding exhaust.

Dave

 

[angus]

If you have a 5-speed with the OEM final drive, then you are at 2000-2500 RPM from 40-55 MPH in 5th gear.

If the car is driven a lot around town, then I would expect a significant amount of time spent in the droning region.

That's why I sent out to eliminate this drone in one of the links I posted earlier. That concept would work here too if it were tee'd into the crossover connection so you wouldn't have to have two resonance chambers (one for the front bank and one for the rear). It shouldn't change the performance and the sound of this exhaust (except getting rid of the specific 105Hz frequency).

Might be something to consider (especially on a daily driver). It sure is a nice-sounding exhaust.

Dave

Well as I said before , I spent a lot of time working on this system and the drone is noticeable but not intrusive certainly nothing compared to nsx exhausts that have the dreaded and annoying drone - I think people are so afraid of the drone that when they hear that this might have a tiny bit , they get worried - well I once had an ark DT-S and it was annoying - also driven a few GTLW cars and it's even worse - I could try to eliminate it completely but I don't think the extra cost is warranted since it is not every car that gets a drone and even on the ones that do it is very mild. Personally I love the system the way it is and also would not want to add any more weight.

I do appreciate your input here as I always like to hear peoples input

 

[Rob4092xx]

I might be the only person on this website that doesn't understand what you mean "drone." Can you please explain it to me? Maybe a audioclip?

Well as I said before , I spent a lot of time working on this system and the drone is noticeable but not intrusive certainly nothing compared to nsx exhausts that have the dreaded and annoying drone - I think people are so afraid of the drone that when they hear that this might have a tiny bit , they get worried - well I once had an ark DT-S and it was annoying - also driven a few GTLW cars and it's even worse - I could try to eliminate it completely but I don't think the extra cost is warranted since it is not every car that gets a drone and even on the ones that do it is very mild. Personally I love the system the way it is and also would not want to add any more weight.

I do appreciate your input here as I always like to hear peoples input

 

[angus]

I might be the only person on this website that doesn't understand what you mean "drone." Can you please explain it to me? Maybe a audioclip?

When we refer to drone, it is a specific frequency (in this case just above 100hz) that only comes in at a certain RPM that is annoying to the ear and intrusive while driving.

The nsx has a propensity for this in a lot of the exhuasts on the market , it is still present yet very well muted in my exhaust - as I said, this exhaust is very tame at idle and cruising and only has what has been described as "a hint" of drone - at a certain load point - I could tune it further but would the added cost and weight be worth it?