The C ratings are largely irrelevant for a Supastox, and wholly unreliable anyway. Within reason, manufacturers can make the C rating whatever they want it to be.
The only relevant number is the capacity. A higher capacity cell will have less voltage drop during a race, and the longer the race the more the advantage. Like Sosidge, I've tried a few and settled on the ones that gave the best lap times in the last minute of the race. They're SMC 5600 cells, and they work just fine. HTH
