Hmm - you can probably run 12psi then, but yeah, with stock ecu you'll get massive rich-and-retard in the middle (like it has MASSIVE lag in the middle of the RPM curve), then comes on ridiculously strong. If you're not used to it, you'll punch your car into a pole.
If you haven't had a turbo car before, set it to 9psi, have a play with that, and then once you're confident (and I'm still assuming no funny business on the roads), then look at moving it upwards.
When I first got my 33, mine was set to 12psi and it scared the living shit out of me. (admittedly with a Power FC so the midrange grunt was back)