All depends on supporting mods
You can go as high as about 12/13 PSI if tuned correctly with the right supporting mods (atleast 600cc injectors, large fuel pump, decent engine management to handle it all)
Don't forget the clutch, diff etc is only made for an NA 3SGE, as adding more strain to those, they will also take alot of abuse.
Best to consult who is tuning your car and see what he is capable of, all motors are different, all tuners are different.
A few people I've sold kits to are running on 10PSI (0.69 Bar) daily with no problems (of course with supporting mods)
But till then, stick to about 6/7 psi max with the factory fuelling after another tune