Just about any kit (Bionix, Crystalite, Falcon) will have a 20" wheel motor. Most of them want to put the batteries in ugly bags that you hang off your rear rack. The E+ system replaces the front wheel with a special hub battery. Nice! Neat. Elegant. Expensive. I think its worth it but I would want to use a donor folder higher up the food chain than a Boardwalk. Just saying.

H