Hi Tom
I just checked which plug I used. It is the MT04-1 and plugs into a connector that is located next to the ECU under the seat. Bonus- the scanner was powered by this plug, so I didn't need to connect the leads to the battery. I'll admit I'm pretty new to bikes with computers, so I'm not sure what the MGMP is or what it looks like. My others are pre-computer Yamahas and a very crusty older Vespa.
Good luck!