Another tip for the Aero Hogs is to put balance the prop. It's a very complicated procedure:
1 Put your finger on the engine
2 Run engine
3 Feel for vibration
4 Place a small (very) on the back of one of the prop blades
5 Run engine
6 Feel vibration
7 If it's better do the same on the other engine.
8 If it's worse, take of the tape, go to step 1 (assuming you will not put tape on the same blad .