Well I bought a turbo today for my Mustang, Precision GT42-76 Turbo, from Turbo306, but I have a few questions. The A/R is 1.28 is this too big? Also it had a 4" downpipe but I only a 3.5" downpipe, is this OK? Will changing from 3" to 3.5" piping from the intercooler to the throttle body worth doing? Will switching from a 75mm throttle to a 90mm throttle worth doing? I am trying to make around 1000HP, I have an R-block billet internal 327 which is a zero balance, Twisted Wedge heads ported by T.E.A., they flow 300 and 217 @ 500 lift, Spyder Intake and a 4500 stall.

 

that sounds like a monster for the little 327. You might have some trouble getting that thing to spool up. it would be better to see a 4" downpipe on that thing but I imagine you could still hit your goal with a 3.5" pipe. But to make the 1000hp I would go big on everything you're talking about. Thats my opinion, hopefully someone else can give some input also.