i was gonna go with the 7xl, but I think i'll go with the 8xl or 9xl for extra run time. They cant be that much slower than the 7xl?

That's kinda what I was thinking, the only time on the track when I'd need speed is the straight, and 35mph would easily be enough because the rest is fairly tight and you can just go off torque/acceleration........which I'm sure the 8xl would be good at.

Coolhand experienced that the 7XL vs the 9XL allmost had no difference in power/topspeed (he geared them both different) and the 9XL stayed cooler and ran longer.

this was on 16 cells.

Well, I think I'd be running 12 minimum (which I know would have a bit slower top speed), with maybe a max of 18.....I'd have to get some more cells though, or at least find another spot to mount 6 more cells.