Do not use the Mamba 4600 motor. It will run too hot. You can calculate your speed using this calculator: http://scriptasylum.com/rc_speed/_top_speed.html

This calculator will help you determine which motor and what gearing to use. The feigao motors are ok but I would get a medusa. Some people have run a single Velineon 3500 but I would not go that route either. The Mamba Max can handle a 4S lipo with no problem or a 5S with a fan or slight modifications. 4S in an E-Revo would be optimal since you can run two (of the same MaH) 2S lipos in series. You could do one 2S and one 3S as long as the Mah is the same but there may be issues with that setup.