you should around 35 to 40 with a 9xl on 14 cells because of the massive amounts of torque which allows you to gear up high for more speed.

you could also think about getting an 8xl which has more power than the 9xl but has better runtime than the 7xl. the 8xl is right in the middle.

what about the system getting "HOT"?

I was also thinking of getting the Gorilla g3 kit, but it stated for the 2.5 emaxx?

it has the 2.5 width which comes stock on the e-maxx now. so it wouldnt be a problem

You won't have any problem with temps on the 8/9XL or on the 7XL for that matter...