I just built a brushed 3903 from scratch with my son. We are using the EVX2 ESC and I have to get some batteries for the truck. I was looking at the EVX2 specs and they indicate 16.8V max and the ability to take 4S Lipo batteries. However, when reading the specs on the Traxxas E-Maxx 3903 page, it says 2S 7.4V Lipos only. Is it because the EVX2 is wired in series (a pair of 2S Lipo packs) rather than parallel (a pair of 4S Lipo packs) or is the wiring of the EVX2 in parallel so that I can use a pair of the 4S to max the voltage and extend the run time? I don't want to fry something and the Traxxas web site is contradicting.