i've explored this avenue myself for a 20v, and you can run a NOS system rated to 1/3 of your engines power figure (on stock internals) quite safely as long as you use it in bursts and don't just hold it on for a long period you're fine.
so...for example
160hp motor
50-55 shot (could get 100 kit and use regulator)
the cool thing about yoshiokas car is that he not only keeps up, but puts out a fair bit of smoke too, something 4A powered 86's don't do when drifting all that much.