my setup is a knockoff t25/t28 turbo on 8psi on a built d16y5.my downpipe is only about 1 to 1.5 inches in diameter so im pretty sure its choking it because when i pop it off it spools quicker and harder.i went to the track for the first time and hit a 14.3 with no downpipe.my question is what size do you recomend for the downpipe?or do you know of anybody who makes a downpipe for a 1991 civic hatch dx other than greddy?and if so how much roughly? theres this damn srt4 lol that runs a mid 12 and i wanna smoke him real bad cuz im tired of hearing him go up and down the local strip

 

it needs to be aleast 2.5 to benefit the spool and topend power... i made my own dp to replace the stock greddy 2" which is really only 1 7/8 " inside diameter..
it made a noticeable inprovement with topend power.. a good muffler shop could make 1 ...

 

the downstraw returns!! I saw a 1.5" DP...it was bad ***, but spool on a 14b was sick.....4000rpm on a D series to spool it....restrictive, i think not

 

1.5 inch?

i have straws bigger then that...

2.5 at least for a turbo car