Capacitors used to be installed on brushed motors many years ago to smooth out the response, but I don't recall them adding any power boost, there is a capacitor booster that is used on the ESC to boost the voltage up to 3S power temporarily and this feature is explicitly forbidden in stock racing, I've tested it personally and confirmed that it works here, this is definitely cheating:


Note that it takes about 20 seconds to charge back up, but if you used it on the straight every lap you would definitely shave your lap times for sure!