The old DOHC ZC is making well over 300 with 11mm studs and a freakin Felpro graphite gasket. (yes I have blown one already, but that was because I fixed a boost leak and had some detonation issues which is what popped the gasket). A little copper spray and back at it I went. Wiseco pistons and CSS kept her alive. I think at the boost levels you're talking, as long as the timing is right and by right I mean conservative for most builds and you keep AFR in boost around 11.5-11.7 you're gonna be totally fine. I'm running max 18 psi on mine (pretty much where the old GT28RS is done), and so far, so good.