stock internals lol.. they rule.. i just tuned a b18c turbo running a percision c50 turbo, at 5, and 7 psi.. its sick son.. it spiked boost to 11.3psi at one point and it didn't do anything damage.. even raced a SC 350z on that 11.3 untuned boost and whipped his ass.. stock internals as shmoo said are compiable of handling up to 320 WHP..the only major thing to really upgrade on a gsr is the rod bolts, head studs really other then that man u can run 10-12psi all day long.