MC21 Wire Splice
The MC21 is restricted in a couple of ways. The first and most significant is a by way of retarding the ignition timing at high rpm. This allows the motor to rev, but kills the power flat.
The second restriction is by way of the gear position sensor (GPS), which sends a message to the PGMIII unit telling it which gear is selected, and then the appropriate ignition curve map is used. The maps used for the top three gears are somewhat retarded, so not really what is needed for good power.