Cheers magman, efficiency makes sense as I was running 2 x 2s trakpower 4900's in series and it was running much warmer but I guess amperage would have been an issue with this set up? These packs punch pretty hard on their own in a 1/10th so does the amperage increase when running 2 in a series?

This whole amperage thing is just another thing to confuse me when it comes to working out the optimum set up......Cheaper and faster than nitro? yes, not if you make a mistake though.