ITSTOCK

I have a 2.5" downpipe coming off the turbo, going into a crush bent 2.25" exhaust at the moment, and i wana upgrade it asap. Justa basic homemade T25 setup on a d16z6, running 7-9 psi. Is it worth teh extra few $$$ to go with the 3" or would 2.5" do the job?

InTeGrA B18b1

3 inch will make more top end but 2.5 would fit your setup quite well.

mamaboy

you'll lose alot of low end with the psi while gaining alot of high end.....general rule of thumb if you are aiming for anything lower than 250 get a 2.5" all the way back

grndcont

acording to severl books and turbo techs, 2.5" is good up to 400hp. and 3" for 500ish. the big thing about exausts is good, smoothe flow. on a d' with turbo 2.5", non crush bent, is more then enuff. just make shure that the air flow is smoothe. oh ya, a big exaust does not kill low end. think about it, why would back pressure help tourq? remember that hp is deterved from the torq outpout, devided by time. the best exaust is the least restritive while mantaning good constent flow.

bigwig

2.5" or keep the pressbent...i would probably use the pressbent..

mamaboy

Read this article
http://www.vishnutuning.com/exhaust101.htm

2.5" crush will do on a d series running that boost level....and the best exhaust for a turbo'd system is no exhaust. 2.5" for a 400whp turbo'd vehicle ???

grndcont

thats acording to corky bell. although it was a slightly dated book. i was going to say the no exaust bit, but we are talking about a street car.