I just picked up a Futaba PCM radio. I have a few guys running the Spektrum at my track and they love it. I am not sure yet, plus I use a LRP Quantum speedo and have heard bad things about that combo. You can get a used radio, helps if you know the person that has it. M8,3PJS, KO Mars any of those are good and the servos by those companies are good too.
Rod