Okay I have decided to finally upgrade to a front mount intercooler. Ive found a good size one at 24X12X3 and i was wondering with my Garret T04 running 19lbs when racing and 8 when just driving, should i go with 2.5" piping or 3" piping. Which would be better for less lag. Thanks.

 

i have the same turbo setup as you and i run 2.5 for the intercooler piping. i read somewhere 3 is only needed when you push 400+hp. hope that helps.

 

bigger pipes increase lag, smaller pipes keep the air velocity up. too small of a pipe will choke the air so it is also a tuning factor. bigger turbos require bigger piping, 3" is overkill for most all turbo applications though.

with a TO4 i would suggest just running the 2.5" piping

 

2.5'' from turbo to i/c, 3'' from i/c to tb

 

Just wonderin why? Thanks.