I've been running it like that since i built it, a few days of practising and a weekend of racing using 23t tamiya motors, and so far no problems. Not sure about mod motors if it will have the same broblem as the evo3. i'm crossing fingers
I suggest you put the second shim in, just watch out for excesive binding if any. Mine was very slight and as i said it gets very free after a few runs. Good luck.