flm Savage has the 6.5 in an E-Savage, which is a similar truck to the E-Maxx, and he says he's getting in the 40s, and hell of a long run time. I bought the Novak 4.5 because I'm building an all out balls to the wall revo conversion, and I didn't want to skimp on the power. However, if I was buying it for an E-Maxx, I would definitely buy the Novak 6.5 because it's powerful, yet gets much better run time. I've heard reports of the 6.5 getting almost twice the run time in the 1/8 buggies. When I buy a system for my E-Revo in a few months, it will be the Novak 6.5. I like the programming capability of the mamba systems, but the motors don't compare to the Novak sensored motors, and I think the sensor will be really nice in a basher. Also, the new Novak HV Pro systems have an upgraded ESC from the HV Maxx, and they offer a lot more programming capability, without the need for a computer. I would reccomend the 6.5 because the run time as well as cooler operating temps will make for a much better basher.