I was always skeptical about higher "C" ratings giving you an increase in performance unless you were pushing the limits of a lower rated battery, until I started racing a stock spec class. In mod class racing it is very difficult to use all of your power, and even with a low rated pack you should still be fast. I dont think there is any more real difference in stock class racing, maybe even less, but that difference can show up coming out of every corner on some tracks, and since everyone should technically be really close to equal, any tiny difference can seem like a big advantage.