RE: Exo Terra build questions and comments
You don't NEED a 550 4-pole; it might be too much for the drive train. I use a 4-pole 540 5700KV Castle motor and it's on the virge of of ripping the center differential out of the car. It hauls the mail on 2S and might be too much for an average race track.
3500-4500KV should be about right; I'll switch mine out eventually. 4-pole 540 can.