It doesn't just let the engine rev higher, it accesses another tune pre-programmed into the ECU (like a switch) that adds more fuel to the combustion chamber due to the increase in air flow and less restrictive exhaust. The "accessible" tune probably has a higher spark timing as well along with other little tidbits.
I don't need more fuel, machines are tuned for sea level, I am at approximately 4250'. If anything I need it to run leaner than normal, for example:
My LT250R is jetted from the factory with a 45 pilot, needle on 3rd clip, a 210 main jet and air screw 1.5 turns. I run a 45 pilot, needle on 2nd clip, a 195 main jet and air screw almost 1.75 turns out to compensate.
Well, I ended up disconnecting the battery, then unplugging the Cherry Bomb, and reconnecting the battery. Hopefully this is good to go.