Contrary to what the other two guys will tell you, the current popular belief is that the FS internals will hold out to 14-16 lbs of boost, so you're looking at pushing the limits there.

FWIW, I don't think you need more than ~10 lbs if it's tuned well. That'd put you in the neighborhood of 215 whp, which would certainly be fun, ~65 more than stock.