I put an XM3500 motor and controller on an ebike that weighed 104lbs total. I went a bit too far with my controller mods, but I had that same controller running at 82V off the charger with a 74V nominal battery and 130amps. That's well over 11,000 watts input to the motor, and I'm sure it would have survived fine at 8kw. If you really want performance, take the battery, motor, and controller and run it on a much lighter strong ebike platform. You can easily modify your controller to do similar with just some copper wire and solder, and as long as you don't have hills to contend with it will survive fine even pushing that heavy pig scooter.
The alternative is to spend $600-1000 on a higher power Kelly controller. If you decide to go that route instead, I'll buy the controller you have for $185 that will help defray the new controller costs. Just send me a PM.
EDIT- As part of the mods, I would also suggest installing the lowest profile 13" scooter tire you can find, which will decrease the OD of the wheel and increase performance.
