I'm currently running like 15-17psi and I haven't had a single slip yet. Granted, I"m still in the break-in process (have NOT launched the car yet...I don't wanna break axles...)but once it's fully broken in, I'm gonna up the boost to around 18 or so. Either way, it feels GREAT and holds even GREATER!

96 Indy Red Dodge Avenger I4 5spd
225.7whp/227.2wtq @ 10psi, currently running 12-14psi.
HRC Stage III turbo setup
JE 8.8:1 pistons
Eagle rods
block bored .020" over
GReddy FMIC w/ custom piping
1G crushed BOV
SPEC Stage 3 clutch
2.5" DP, 2.5" high flow cat, 3" ERT catback w/ Magnaflow muffler and 3" tip.
much much more...