well you could push 10-12 on a stock GSR...couple of internals and others a little tuning some where's aorund 18...fully built out the ass and you could make it hold 30 psi...it is possible because GSR are better built to withstand boost...i know it is possible because i have seen a couple of Ls with and without vtec converison hold 30 psi and make around or at 600 whp but it's a honda so torque was shitty