I would like to know the important differences between 540 and 550 motors. I know that Emaxx trucks use 550 motors. Recently, I got a Stampede. The way I understand it, Stampede's can run on 540 and 550 type motors? So, when I am looking for a faster motor, should I be looking for a 540 or 550 replacement? Are 540's faster because they are smaller? or drain less power from the battery? or are 550's stronger motors? I see many cool motor options, 15T, 17T, Amber speed gems, etc.. Some are 540 and some are 550 motors. I would like to understand why I am choosing a 540 or 550 motor replacement. Thanks to all.