My 501x Worlds Edition, that piece of foam(outa a novak box) I shoo gooed to the body is to allow air to pass through the body to cool the motor.
Due to the fact I'm running a Tekin R1 pro speed control and 362 brushless motor, it gets barley warm after a heat race. Stock gearing.
I re-built the rear diff so it's butter smooth again. Front one way.
I added an aluminum steering bridge/new front shock tower to the car recently(not pictured), looks like I'll have
a bit more steering this next big race next weekend.