Average Safe Boost level for a LA eng

I ran 6PSI of boost on a Fel-Pro 1008 gasket with ARP bolts.

I did get tired of "pushing" the gaskets out, I have since O-Ringed the heads and cut receiver grooves in the block and run SCE copper head gaskets.

I dont think my tuning was off or detonation was to blame as I have whacked stock pistons with 6PSI off boost WITH upto a 200 shot of N2O and never broke a piston from detonation. LOL However it is real bad for stock pistons when the needle on the tach goes past 8,000...