I have a 13b-re in a fc. The TB inlet pipe is 3". Would running 2.5" piping/ic up untill that point cause any loss in performance?

 

I think that most people would suggest running the 2.5" piping for anything less than like, 400whp or so. So no, you wouldn't lose performance--and might benefit from the better boost-response/spool of the tighter piping.

 

Im running 2" piping on my 13b-re with a t04b V-trim 1.00 ar . My goal is 280-300 rwhp . i think i'll be fine . I haven't run it yet (waiting for a turbo manifold) if your interested i'll let you know how it goes . If your going for more than 300whp i would go with 2.5" .