I am building a 3 inch exhaust for a GTi-R swap. What is the best size for a downpipe? Should i just make a 3inch one? I will be running no cat if that matters

2.5 or 3 inch from downpipe to the muffler is ideal for a turbo setup (the bigger the better since turbos don't like backpressure unlike NA cars) . Find yourself a turbo muffler while you're at it( maybe an Apexi N1, or Dunk will do some good)
Hope this helps,
Nick

i have the gtir in my 200, and the downpipe from the turbo is 2.5 inch, from that bend back it goes to 3"....the only reason we didn't go 3" on the downpipe is that it would have been lower than the crossmember, and that's not exactly a good idea. if you have the room, go for it, but i didn't

Same here. I have a 2.5" downpipe, its all I could fit on the B12, but 3" is always better if it can be afforded. Good luck!
John

You do know HKS makes downpipes for the GTiR right? HKS takes about 4-6 weeks to get stuff sent over from Japan/Europe!

Originally posted by APEXSER
You do know HKS makes downpipes for the GTiR right? HKS takes about 4-6 weeks to get stuff sent over from Japan/Europe!
Are you able to get the HKs cams as well in different grinds?

depending on what turbo you go with should determine the size. if you want faster spool up go with a 2.5 but if you don't mind lag then say forget it and get a 3 in. i had a 3 in on my t28 but i went with a 2.5 with my stage 5 ballbearing 60-1 hi flow. and that spooled up alot faster than my t28.

jimmy
1996 200sx gti-r motor

Originally posted by SucKit

Are you able to get the HKs cams as well in different grinds?

Yes I am! Let me knwo what you are looking for!