Nitrous oxide kits can be found at any speed shop or mail order performance parts dealer.
Do your homework & get the right kit for the car.
Don't do your homework or follow instructions carefully, & your engine will be toast.
VQ35DE has a short top piston ring land....which means if your engine is functioning under 'detonation' conditions, you could break a piston easily.
Things to be concerned with: extra fuel, timing retard when n20 kicks in....
There are some threads on the board. Search them out & read 'em!