i am running on 1bar...which is around the 14psi...that is da max (so called safe) boost you can hit on the turbo....but anything higher will blow the turbos very very quickly...other than that dont think there is anyother issues...car wouldn lean out due to the stock ecu...from what i have heard the stock ecu will adjust its fuel ratio according to the boost...unlike the aftermarket ecus...
pete..is stock really 11? i was pretty sure it was 7...