they're supposed to be super strong, so they're harder to blow. I guess this is good for people who like replacing rings or other engine components.
Ideally, your stock replacement head gaskets should not blow if the car is built and tuned properly. The pressure has to go somewhere, so putting a tougher head gasket on a car that isn't set up properly just makes the pressure escape through the next weakest link: rings, seals, etc. You want your head gaskets to be the weakest link because - relative to the other parts that could potentially be damaged if subjected to excessive pressure - they're the cheapest/easiest to replace if need-be.
That's what I've read in the past few years of reading similar threads on here.:SNSign:
They're definitely not intended for an "almost" tune. They're good for combos that use elevated boost pressures or lots of N20 where lockwire gaskets might be used. Extra prep on the both the deck and head surfaces are required.
i had a o ringed block and i popped 2 gaskets on 2 power runs on the dyno, then i put the cometic gaskets on and i have had no problems since. they are also reuseable which is nice
but like others said make sure the tune is dead on cause if the car detonates your gonna have way bigger problems than pulling the heads off