Every one has there own opinions on how much boost a stock turbo can handle, but there are so many variables that can cause a turbo to destruction for one how many K's the turbo has done, the life the turbo has had, how the person drives there car etc, I have recently brought an S2 R33 turbo for my R32 I took the time to find a turbo that was in really good condition that came off a stock car which had not been boosted therefore I knew the turbo hadn’t been thrashed. Its on my car now and I have been running 13psi all day every day and it hasn’t missed a beat, to be honest I wouldn’t run anymore boost then 13psi but I also don’t think 13psi is over boosting it, however I only ever really hold full boost for more then a couple of minutes when racing people. I also have supporting mods, which helps. I definitely agree that if your car is stock as a rock and your running 12psi+ you are asking for trouble
Also for the person who said all R33 turbos have steel compressor wheels is wrong. Series 2 R33 turbos are the same as R34 turbos and have a nylon compressor wheel.