I think comparing the G35 to the GTR and 911, is insane. Yes you could make a G35 with insane hp, and decent straight line speeds, but, the 911 and GTR will also turn corners at insane speeds and be an all round, circuit OR drag strip beast.
I can't imagine the amount of **** you would need to do to a G35 to make it in the same ball park as a 911, or GTR across all categories - straight line, circuit, level of fitout etc etc.