I am thinking about getting a bigger down pipe for my greddy kit (95 single cam vtec, greddy tdo4h turbo) the down pipe that comes with the kit is tiny. Anyway my question is if my catback exhaust and test pipe are 2.5'' in diameter is there any advantage of having a 3'' down pipe or should I just get one that matches my piping diameter? I know down pipe diameter can effect gas flow greatly, but would an over sized dp work better or just cause the bottle neck effect?
-Derek-
.afterdark.

 

Actually, with the small size of the wastegate on the TD04H, it might be best to go with a smaller 2.5" downpipe and have a larger testpipe and catback. Too big a downpipe and you're inviting boost creep on a wastegate too small to maintain suffecient pressure with a 3" downpipe. I'm going with a 2.5" downpipe, 2.5" testpipe and 3" catback on my 98 EX also with a TD04H.

 

Thanks for the advise I checked out your site, I hit a 14.3 with the same set up if you want to swap secrets hit me up dhearn1@uic.edu, later.
-Derek-

 

Thanks Derek, I'll mail you this week so you can tell me what you've got cooking over there