Depending on what direction you want to do a 6s option would be http://www.helidirect.com/quantum-outrunner-brushless-heli-motor4125-560kv-p-25512.hdxThat being said I am in the process of moving my E5 into a 606mm 7s (5000mah) bird using a Scorpion 4025 890kv motor. Sent from my SAMSUNG-SGH-I747 using Tapatalk 2