I'm running 6s batteries in my rc8Be for a different reason than breaking the land speed record. I slapped a 1400kv t8 in there and use 2200mah batteries for a ten minute or below heat, and use a 3000mah battery if I need to make 15 minutes. These batteries weigh considerably less than a comparable 4s setup. The lower kv motor with the higher voltage batteries gives the smoothest power delivery I've ever felt, not to mention the efficiency the system runs at which leaves it much cooler than many of the 4s arrangements I have run. My latest project has been to put this car on a diet. I've shed weight in about every way I can think of, lightened pins and turnbuckles; and I'm about to test out the SNR carbon fiber chassis. I've knocked in the neighborhood of a pound off my car and I can't wait to see what it does on the track.