I looked in to this, i spoke to RS
The RS flywheel is made and tested and gives the best output from the Rs stator.
You would get a better output from your stock stator with an RS flywheel due to the stronger magnets in it but no where near what you will get if you fit both the RS 200w stator and flywheel.
I have both sat waiting to be fitted along with a battery and some hid lights.