go with 3" if you have some head work done which will be taking the increased amount air flow from the turbo and throwing more of it though the engine.

Port and polished heads
4 angle valve job
Lighter and 2 mm bigger valves
Bored exhaust ports to equal intake as much as possible

thats what i reccommend to have done to run with some more boost and successfully 3" piping. if you don't plan on doing any head and/or block work go with 2.5" piping.

 

Unless you gut the cat out, you'll have plenty of back pressure. Even with a high flow cat and a 3" exhaust from the turbo back, you'll still have enough bp to keep you going pretty strong.

 

yea the 3" exhaust pipe won't hurt you much.

 

man you people need to search the board...some of you dont know what your talking about.

 

I am building a d16z6 completely balanced and yes I will have head work as well...I am using the apexi turbo kit...The turbo can generate up to 22lbs. of boost, I will most likely be running 16-17psi after the fuel system is up to par. I was told I have to run 3" by some and others said 3" was too much. Just trying to get as much info before I go out spending all the money I don't have.

 

sounds like your gonna have a great set up. go with the 3" pipe.:thumbup:

 

no way man... go with a 8 inch pipe.. i JUST heard they are the BEST...

 

APEX-i GT Exhaust its 3" i think

 

A turbo is exhaust-driven. The turbine relys on these exhaust gases to 'spool' up.'

In my opinion, a 3" exhaust will still see gains with a little turbo/low boost. It sees much more power at higher boost/larger turbo applications due to reduced backpressure; thus, enabling more exhaust to flow per unit of time.

 

3" pipe is overkill with a 4 cylinder engine, unless your running ALOT of boost. 2.5" is more ideal for a turbo civic.