Errrr........ there have been different rotors available for other motors for a few years now, this isn't anything particularly new.
Different rotors will alter the power band, making it more torque-y, more rpms, a narrower or wider band - depending on the rotor - so yes 'some' will increase the top speed, others won't.
AFAIK, all these rotors (and others from different manufacturers) are perfectly legal for mod classes, so no need to tech them.
If you're looking at 10.5/13.5/17.5s, then just measure the diameter of the rotor and the shaft.
Oli Meggitt | London, UK
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