This is a much more complex issue than it seems. There is no easy way to add a lot more power to the NSX and do it on the cheap. Everything has a limitation and nothing is as good as OEM for reliability. Then there is the whole question of devaluing what is basically a rare car with this. As of today, I have $140-150,000 into my NSX, and my engine is stock short of headers and exhaust. I have a lot of personal opinions on this, but can say for sure no one thing is superior and something will always be better for a particular application. To me, what needs to be worked on, is an option to drop in a V8 Chevrolet block. Now many may poo-poo this idea, because it may not be Honda, but the LS/LT engines are small so they can fit, they make real power and torque, have more aftermarket support than anything in history, and are NA and incredibly reliable. They also sound fantastic. All of this comes at a very reasonable cost, for less than the cost of a CTSC system you can get a brand new GM crate engine, and take your C series and store it some place safely. Weight remains pretty much the same.
Another major thing rarely ever discussed is the fact that you can make all the power you want, it doesn't mean the NSX transaxle has to like your idea and not just decide to give up. Axles, gears, transmissions, will all start breaking much north of 450 HP. So realistically, you have a natural limit there. Cody had come up with the idea to rotate the engine, lower the CG, drop in a dry sump, improve the handling, run an LS, and use a Porsche transaxle that could hold 700+ lb/ft of torque if need be. ShaylorD here went with an SOS twin turbo, car makes more than 800 on E-85, and now his transmission is having issues. The other thing is the clutch, high HP clutches seem to me very stiff and take away from the driving experience. Trying to make an NSX's small clutch handle torque requires compromises you don't have with a more modern gearbox/clutch/trans.
Transmission is a problem, Fuel becomes octane often becomes a limiting factor (hence E85 and Methanol, both of which have drawbacks of their own), hacking up the car becomes a problem.
Here are just some of my quick thoughts:
NA- best response, transmission life, general reliability, high cost gains and limited power.
CTSC- Most simple of all FI systems and legal. Compromised fueling system. Never 100% accurate fuel delivery. Extremely high resale value. Easy install and removal done in a day. Loss of power under sustained use because of heat.
SOS supercharger- CTSC made complex and costly. More powerful, better fueling, not a good return on investment IMO once you add in intercooler, engine managment, etc. I am personally not fond of AEM.
Angus- I don't know enough about this to comment.
Lovefab- Cody is a friend. He is a real no bullshit guy. Cody cares less about nuance and refinement than about actual results. What he makes works. Be it a turbo kit or an aero system or a chassis bar. If you really just want raw power and results in anything, he is your guy.
Shad/driving ambition- I can never get a hold of this guy. He is quite knowledgeable and if you are in the vicinity and can get him to actually work on your car, go for it. He knows his stuff. He makes a nice intercooler that is far superior to what SOS used to make and can make a CTSC low boost or high boost, run perfect. If you are far away and need to deal by phone, good luck.
SOS twin turbo system- well designed and powerful system, but expensive. A lot of potential that can justify the cost, only your OEM engine and trans will limit you to the low/mid 400 range and well... you've spent a lot.
Dave Dozier's: This has long been a favorite of mine. Dave has a lot of attention to detail. IMO this is the most well-designed system out there. I don't love the AEM he tunes with but some of this is personal. I can tell you that Cody dropped AEM and decided to switch to Haltech. Having looked deeply into engine management I like Emtron of Australia. They are related to Motec. Back on subject.... The turbos dave uses are self contained. No oil or coolant lines. This simplifies things, allows more locations for the turbo, and reduces points of failure. The way the whole package bolts into and out of the car is ingenious. The response for variable vane twins is second to none. There is no waiting. The intercooler design is near perfect. Dual pass and inside the intake. The pressure loss is so little. The results speak for the efficiency. Boost is resistance. You want the highest CFM with the lowest PSI. Keeping things cool means more power with less stress. Don't forget engines are less than 50% in terms of thermal efficiency. Half the energy in gasoline is making heat. It is better to be more efficient than to just make more power because the first comes with less stress on all components and more longevity. Dave's numbers show... the system is efficient. What I am not sold on are the reliability of the turbos themselves, he is fine with it, and probably knows well, but certainly as far as name goes, aerocharger is not Garrett. This system isn't cheap either, like the SOS twins, but I personally like this a bit better. It's just less complex, more OEM. Still really considering this for myself at a cost and level way beyond my old CTSC.
J-swap: This is an option that needs to be considered by more people IMO. For the cost of forced induction you can swap to an engine with dirt cheap parts and support (an entire engine can be had for $300-500). If you turbo it, it makes TORQUE. Cody stopped developing parts for the C and moved to J support. Run more boost. Blow it up. No worries... your cost of a repair or replacement are minimal. Thousands lay in junkyards. Dimer Van Santen who races his NSX went this route. we are talking 10K for a new J installed in your car while the rare and expensive C stays safe. A J makes significantly more torque than a C at the same boost levels because of displacement. You are starting off at 3.5L in many cases. That's a stroker C for $500.
Now these are all my opinions, and I did not write this to offend or upset anyone. Being at the track, I realized I still have a long way to go before I can say "OK the engine is holding me back". The weak link is still me, although I have been on the track 5-6 years now. I went back to NA by CTSC removal and for sure lost power... but the engine seems more sprightly... it likes to rev more, reacts to throttle better, sounds better to my ear, and when working on the engine, everything is a nicer OEM fit instead of stuff crammed into the passenger side. I also no longer leak a drop of oil, and Vtec is back. I missed it.
Midnight Raven and I are good local friends, we work on our NSX's all the time. His 1991 coupe is under 2700 pounds. My 05 with a tank of gas is probably 2950 or so. We both have a 6 speed. He has upgraded. He just has a 3.0 with 100K miles, and I have a 3.2 with 28K miles. My car out-pulls his despite the weight, despite the identical transmissions. You can feel it from behind the wheel. I feel many just dismiss the 3.2 as "only 20 more HP" but they feel different because of torque and the power curve. I know this will cause a lot of arguments now but I am going to stay out of those. Again, my OPINION is just having a 3.2 is of useful and noticeable benefit.