My FMIC has 2.5' inlets....my trottle body has a 2.5' inlet as well.....most of the turbos I've been looking at have only 2"outlets....at what point in the piping do I change pipe diameter? At the turbo, at the FMIC, elsewhere?...or just find a turbo with a 2.5" outlet and stay the same size the whole way through?

 

use a transition 90 degree coupler right off of the turbo to 2.5" piping there to the intercooler and intercooler to throttle body. Thats how most people do it or you can use a little smaller piping before the intercooler and 2.5" from intercooler to throttle body.

 

just use a 2-2.5 coupler off the turbo.

 

wouldnt 2" from turbo to intercooler and then 2.5" from intercooler to TB have better spool time?