I would say your biggest issue is you are running 2c (7.4) volts. That's alot of power for 1/12ths. For about the last 15 years most (if not all) people are running 4.8 volts max. I bet the cars your driving against to compare are probably running 4.8 or 3.7 volts. Once you change down to the proper battery I bet the car gets better. Make sure you are also running a competitive body against the others. Downforce is extremely important.
Steve