the pressure you should run, is the pressure that the vehicle was tuned to run...
so, in other words, get it on a dyno, wind a little bit of boost into it at a time, and check for detonation, check the AFR's etc.
however, having said that, at a guess, around 14psi to 1bar 'should' be okay, providing everything is in good condition, like ur fuel pump etc...
again, get it on a dyno and check, don't go by a 'generic' answer that someone gives you online, as each car is different