I run a xxxt mf2 with a Novak GTB and a 6.5 with Maxamps 6000 geared at 17/86 on a big track. It will run 20min+
My daughter runs a xxxt mf2 with a GTB and a 13.5 with maxamps 6000 geared at 21/86 on the same track. it will run forever!
The sad part is I run the same laps with her truck as I do with mine.
I just like being able to do a wheelie down the straight with mine.
here is a link to the track for some pics.