In first gear my motor won't boost past like-- 3-4 Psi on my LS. I'm running a t3/04e 57trim .63A/R. Is it because the Turbo is too big-- or is it because i'm running open downpipe, and there isn't any back pressure?? I basically have like a 1foot downpipe.

 

prolly due to the ar size

 

no, that turbo should spool fine it's not huge. check for leaks in ICpiping and vacuum tubing

 

what should i check for on the vacuum lines?