The PGM doesn't restrict the speed in itself, it's the ignition unit which takes input from the engine RPM, throttle position and gear selected to give an output to the coils which produce a spark at the right time. It has a different curve for each gear, and has been designed to restrict the power in the top couple of gears, as well as a circuit which restrictys the top speed.

Both of these can be bypassed. The speed restriction is bypassed with the M-Max, and the high gear retarding by doing a little mod to fool the PGM into thinking it neer gets above 3rd gear.

I have an HRC de-restrictor, which does both jobs at once.
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