"Ye canna change the laws of physics"

I see a new piston or set of valves (if you are lucky) in your future.

If you want to test for real power, put it on a dyno. Otherwise this seat of the pants stuff is in your head and what you want to feel.

You have a supercharger. It's a forced induction engine. Despite the stupid sticker Nissan puts on the gas cap door, use Premium or you risk damaging your engine. Esp. in the summer when the heat is up