All I can really add from experience about plugs is do NOT put an OS plug in a novarossi. You will for sure screw it up. McCoys are OK though if you cannot get novas...

I also advise using the plug recommended my the manufacturer. After all they designed the motors and the plugs and they for sure will work together.

My guess would be that plugs that work in Novarossi's and RB's should also work in GRP's, since they are all manufactured by novarossi. But dont hold that against me if im wrong.