It depends on your turbo more than the block itself (ej20). If you've got the stock turbo, you should not let it peak above 17 PSI. The normal peak if you want to turn up the boost is about 15.5 or 16 PSI. If you upgrade your turbocharger and add the necessary supporting mods, you could potentially boost 25 PSI or higher.
BIG turbo, no cats, big injectors/fuel; pump, lot's and LOT'S of tuning. Even with GT30R I could not get more than 22 PSI out of it on 93 octane. On race fuel 28-30 PSI was no problem. Then again PSI makes no difference. I assume you want power and not just PSI. That's a whole different question. I think you probably have a LOT to learn about turbo cars.