The F3 MC21 kit uses an RS250 PGM-II, but that is slightly different to an MC18 PGM-II.

It would indeed be taking a step backward, fitting an MC18 PGM-II to an MC21, unless of course you PGM-III is dead and you have an MC18 unit and harness to hand!

As Stephen rightly says, the MC18 has no G.P.S. The PGM-III uses this, in conjunction with the T.P.S. and an it's internal RPM sensor, to alter the ignition timing and PJ solenoids according to each input parameter. This makes the system much more tunable, and consequently, the power delivery much smoother.

Andy.
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