You're just getting more complete [read powerful] burn out of that same compressed mixture. Of course, if you don't supplement the fuel, you burn pistons in no time.

[edit] back in my racing days (1968 Camaro, 327/4 speed/12 bolt rear w/posi 4.10:1 gears] one of the clowns I knew installed his brother's NOS injector plate upside down. Some sort of explosion resulted.