If you need to be R.O.A.R. legal you have to run 4 cell (in a hard case). With 4 cell, a 2200Kv too 2600Kv motor would be the range you need. I don't care about ROAR. I run A Neu 1512 3df (1700kv) with 6S 2600 mAh cells in my MBX6. The mains at our local track are all 10 min or less. I used the RC Products design MBX5 conversion kit (required me to drill some new mounting holes in conversions battery tray but not a big deal). I'm using the Mamba Monster ESC's in all my set-ups.

P= I x V
P= Power
I= current
V=voltage

If "V" goes up, "I" goes down to get the same amount of power.

More efficent.

I've had my X6 since september, run it every weekend. Have'nt broken to much stuff.