40 Watts out of a more efficiently switching R/R? There will be some improvment but that number is bullshit....
If you want MOSFET I would go with OEM quality, the Shindengen (manufacturer of >90% of all OEM R/Rs) ones can be had for less.
Get this one:
and a set of high quality Japanese connectors to replace the cheap KTM OEM ones:
Forget about putting on a 950/990 stator, will never fit properly.