MAYBE if you didn''t go over 2 inch you might see some gains in performance and mileage. I had 2 1/4 on one of my TwinCam S-Cars and it did nothing at all for the 1/4 mile or fuel mileage. If I had to do it over again I'd go with 2 inch all the way back.

 

o ok i c thanx

 

I did the exhaust after I did a big bore throttle body and intake.

Throttle body and intake combined I saw an average .168 quicker 1/4 mile runs on three of my twincams

 

2 tenth''s just for that....not sure about that one

but here is the thing. Why your gonna see worse mileage with a header is the o2 sensor is now gonna read worse #''s and it will call for alittle more fuel consumption. Probably not enough to even be noticable.

and i think the only time youll "think" you have better mileage on an intake is if your original filter was very dirty, so when you put on the CAI your dropping in a brand new filter and thus getting alittle better than before

 

now with the o2 sensor, would a wide band o2 sensor solve this problem?

 

go no bigger than 2.25 inch for all motor if youre gonna put a turbo or supercharger then go 2.5-3.0 inch for that integra i hope there was a turbo cuz 3.0 inch for a n/a 4 cyl. is just dumb we dont have v6 or v8 we still need some back pressure 2 inch pipe new cat., cai and headers will improve fuel economy but not by much youll gain some mid range power as well as far as o2 sensor i hav no idea

 

ok 95_sl1 if you still hav the integra with a 3 inch catback and r located in st. paul, mn i would totally race you to show you that 3 inch is too big for n/a