500 Watt through 1000 Watt motors have been successfully custom installed on the E300 electric scooter. The motor can be installed in the original position or in the top of frame position. Each motor mounting position has its pluses and minuses. Top mounting requires modifying the footplate, and bottom mounting requires repositioning of the brake or brake cable. There are bound to be other custom installation tasks that need to be performed for each motor mounting position, but figuring that stuff out while custom installing parts is half the fun of the job.
When selecting a Lithium battery pack the pack's continuous current output rating needs to be higher than the controller's maximum current rating.