Hi there, I've bought an R33 GTR with a single turbo conversion. Its a monster, and its pushing 275rwkw at 15psi; when tuning it they increased the pressure to 17psi and it pushed well over 300rwkw, but they wound it back to 15psi because they said the stock head gasket wouldn't handle it and I need to replace it, the pistons, and conrods before looking at the injectors and fuel rail. I was under the impression the stock internals would be good for up to 600hp; are the forged or not? how much psi can the head reasonably take? I'm sure there is a thread on here somewhere about this but I can't find it, so would be very appreciative if someone could give me some answers.