Yep, anything substantial over 200 is pretty much the dyno. I wouldn't be going past 12psi either as already stated.
Even following that rule, it's still hit and miss. People like Paul have been running 12psi on the stocker for years, no worries, I've had mates turn the boost up to 12psi, put it on the dyno to tune it and go bang on the first run.
Mine lasted a while, probably over a year from memory, then it let go at DECA and unfortunately took the engine with it, so it's a pretty big gamble