I was standing close to a tight turn on the track the other day. 9 ot of 10 of the bodies would rub and cause a spin out or a hook. I dont see how trimming the body can be looked down on by the track. As RobMob mentioned, do you have to use the Stock Traxxas body? i would think not. If you can use another body then trimming the one you have is a given.
I took close to .5 inch off all four.