exhaust question
 

will my 88 n/a supra not run as good with no back pressure o nthe exhaust bucasue right noiw i have a header and a cleanedo out cat the goes to a muffler on the end would it be better to have a littel beack pressure or does it matter

you know what i perfer having practically no back pressure cuz back pressure can cause lost of power im about to get rid of my 3inch exhuast for an apexi GT series that runs 3.7inch with a i think 4.5 inch opening

you will lose low end and maybe gain top end.

your engine needs a little bit of backpressure for scavenging purposes.

Indeed. From what I have come up with on the N/A's ,a 2 1/2" exhaust is the most you want. Or some have said ,if you know someone with a turbo upgrading ,get that off them and swap it on. I don't imagine your cleaned out cat would have a negative effect with the other elements in place. Unless you took off the resonator and have a more free flowing muffler on there.:dunno: