stock HG is good til about 350whp, but since i know how u drive, going any higher then like 320whp, id do gasket/studs

id do a 264/264 combo, but 300-315whp is pretty much peak HP levels of a GTIR turbo, anything past that ure gonna start baking ure oil.

you need to be running rockerstoppers right now regardless, high rpm stints without stoppers is a BAD idea, its the best $80 you could spend on the safety of that motor

are you running sidefeed or top feed 480s right now? if they are side feed, you could get 330whp max out of them, if they are topfeeds, your pretty much at the max duty you want to be at, since sidefeeds have better cooling via the fuel flow, you can run high duties on the sidefeeds.

im shooting for 290-310 WHP with my GTIR, manifolds, and rom tune only