I agree with kufman! Increase voltage, NOT decrease. Reducing cell count will putmore demand on the cells. Meaning you will have to purchase the TOP of the mached heap to be competetive. 4 cell packs cost MORE than a 6 cell pack! I am not talking oval here.. they are allways stuck with having to buy the highest run-time numbers. In road course and off-road mod you can buy batteries with good voltage & low internal resistance but don't need the highest run-time numbers. That would change when you lop-off a couple cells. I was racing for Schumacher when ROAR went to 6 cell. 4wd off-road was my class of choice. Prior to the rule change, I ran 7 cells with a mild mod (12 - 15 depending on track size). I could gear it concervitavely and NOT be disadvantaged against anyone! Long motor life and lot's of speed & power. After the switch to 6 cells, I had to run 8-10 turn motors to get the same performance (actually could not quite match previous levels). To make matters worse, Schumacher had recently went to a 2.0:1 internal, making it impossible to properly gear a low wind motor. I had to cut comms every run and still toasted the motors in short order.
Reducing the cell count (lower voltage) puts far more demand on the batteries and motor. This results in higher costs for the privateer! Furthermore, you will likely have to run a receiver pack to keep enough voltage in the receiver. On top of that, many of the cars today (on and off-road) are designed to run 6 cells on one side of the car w/ all electronics on the other, to get proper balance. I realize we can shift stuff over to compensate, but why bother?