3.3 conversion! I put a battery tray on both sides and run 6S2P A123's or 4S Lipos, it's incredibly tough for bashing and handles like a dream. For me the main reason I went with a conversion was cost, I picked up a roller for $75 and put in a 3906 trans with a MMM/Medusa, built some batt trays and was driving! Considerably cheaper than an E-Revo!!