3" downpipe power increase?, about how much? Options

[easternpiro1]

Hi guys, Ive been wondering how much HP increase do you get when you add a 3" downpipe to your turbo setup? ive been told in the past at least 10hp, but before making a thread i decided to do some searching....

http://www.mr2oc.com/showthread.php?t=2714...horsepower+gain

and now I have a headache...

on our 3s its obvious that a wider diameter exhaust makes room for more power, but ABOUT how much typically?

I actually read 98% of that thread, and while VERY informative, i didnt get a question answered after all the searching.

anybody know the answer?


cheers!

[PhoenixTech]

Allow me to shed some light on this. Prior to finding out that Matt's engine had a bad head gasket, and then in turn needed OS pistons, the engine held 18psi perfectly with no boost creep. VERY VERY strong pulls all the way through the RPM band, even though 1st, 2nd and initial part of 3rd gear are utterly pointless. (Matt, you need wider tires, 225s ain't cuttin it ) We are controlling the boost via an AEM Tru-Boost gauge/controller. Also, Matt's exhaust is 3" downpipe to 3"...um...."where-the-cat-should-be" back system. Very free flowing exhaust. With that itty bitty stock turbo that's currently on the engine, there was no surging, or boost creeping like you see on a 1JZ or 2JZ with a full 3" exhaust. With Matt's car properly tuned, and with the water meth, we should see 285-295whp at a "reasonable" amount of boost.

-Cam