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!

[delusionz]

Most GT4s ex-japan are fitted with 3" aftermarket systems from the mid section back to the tail, as mine was, the standard portion of exhaust with the flexi and mini resonator tube tappers down to 2 1/8 inches, which i had the entire lot replaced with a 3" system from the back of the turbo through to the tail and it barely made a difference on the stock turbo, pound for pound it was a little faster to spool up, acceleration was a little bit better, car weighed a little bit lighter, etc....

in itself not so much gain, a full 3" system is just good preparation for when you get a big turbo, and in that case your better off going 3" cat-back and only getting the 1 downpipe made the day you do upgrade turbo & manifold