Well personally i dont fink the engine internals are strong enough to handle the power. I guessing you'll need to change internals, as well as upgrading injectors, fuel pumps...etc... But i've been told you can run up to 18psi on stock internals.
Though it would be nice to beat a GTR very hard though! Goodluck buddy! Take me on first parallel boy! Hehe you know what i mean Supra! hahahah