Thanks for correcting yourself, Ryan. I thought I was going crazy or something(I knew you had a 7xl, but couldn't figure out why you were aying 9L). 5S Lipo would be the way to go IMO. It will have more torque than the 18 cells you run, less weight and close top end speed (maybe slightly lower, but not noticeable, really). A pair of 5s 4400 mah packs would get you a nice runtime and nice power.