So your logic is it's better to gain 10whp at peak and lose 15whp between 4-7000rpm's correct? For an NA S2000, it's been proven that 70mm single exhaust will yield the most power throughout the powerband which is 20 times more important than peak numbers, 80% of this forum has no understanding of that.

Exhausts that meet this criteria are, Amuse R1000, J's Racing 70RR, T1R 70mm and the soon to be released T1R 70RT and updated T1R 70mm.

 

if i had a dime for every time you say that.........

 

Actually you don't want backpressure, you want to keep the velocity up for effective scavenging. Ideally your whole exhaust would be coated, but no one goes to that extreme.

With loss of velocity you loose the low and midrange power but you are still able to make your peak numbers. For street driving your car will feel and be slower.

My issue with that type of system is the noise. I tried it (at 2.5") and it was simply too noisy.

With the exhaust uncorked just after the cat I just had to drive it around and see what the 'ultimate" power would be and it was horrible!

Not only did I have to put the gas pedal down much, much more to accomplish the same acceleration but the noise level was greater than any car I have ever owned. It was so loud there was not a piece in the car that didn't rattle.

 

Doesn't seem to be effecting my cars midrange power at all. infact with the install it seem midrange has improved dramatically, and top end feels good aswell.
In no way do I feel losing 15whp midarnge to gain 10 up top is a good thing. I thought of this as I made my choice of the exhaust, and through research, and finding reviews of other s2k owners, the 3 inch seemed like the way to go. Like I said it did improve my midrange power greatly.

I found that a 3inch exhaust will actually make less power on "our" cars(meaning the s2k and not some NA civic), then a 70mm would. However once a 3inch is combined with a test pipe then the gains are better then a 70mm would be with a test pipe.

The whole thing about needing backpressure is total nonsense with our cars. If your worried about back pressure then go with a 2.5 inch. then line up with someone who has a 3inch and do a 5mph roll. see which car gets up to speed faster.

Might seem like I'm talking nonsense but it's probably because I just can't explain myself well. From my experience 3 inch is perfect....anything bigger may be a bit much.

Oh please point out who has proven that a 70mm wworks best for the S because I haven't seen the tests????

 

was this with a 3inch system?

I haven't had to give extra gas to accelerate at all. The car pulls very well and actually i think I apply less gas then I did when I was stock(but thats probably due to the noise level).
Also the bigger the piping should make the car quieter. while the exhaust will still be loud it's much quiter then say an invidia. believe me it's amazing how quiet my set-up is compared to the invidia. While it still growls outside there is barelly any dronning....and this is with a test pipe. while i've heard other 2.5inch exhaust horribly louder, and with insane drone in the cabin.

 

doesnt the size of the muffler pipe determines the whole pipe size.
if the size of the muffer pipe is 70mm then you should do the whole exhaust the same size 70mm. HKS offers their hi power and carbon ti muffler in thier website and it list the pipe diameter on it. 63mm and 70mm for the hi-power exhaust.
you dont want to have bottlenecking in your exhaust.
its better if the exhaust gasses travel on a pipe that has all the same diameter and less bends

 

true but HKS also has a turbo version of there HKS Carbon Ti which has a 3 inch inlet. this is what I went with.

 

You don't have a clue on what you're talking about and no matter what I say to you, you won't understand.

Please read these:

http://www.warnertechnology.com/Cars/backpressure.shtml

http://www.proficientperformance.com...k_pressure.php

http://www.miata.net/garage/KnowYourCar/S4_Back.html


A 3 inch exhaust is ridiculous for a 2.0L N/A car.

 

I know exactly what I'm talking about, and I do understand exactly what your saying and would normally agree with you considering the car, but it's not the same for the S.

I know about backpressure this, and backpressure that, but this does not concern me when it comes to my car. However if I was still driving my AE86 then I'd consider a smaller diameter pipe as it is no where near the same as the S.

 

I know exactly what I'm talking about, and I do understand exactly what your saying and would normally agree with you considering the car, but it's not the same for the S.
I know about backpressure and what it does, or what it's said to do also, but your links prove nothing about how well the "S" responsed to 3 inch exhaust over a 70mm exhaust.