Trust me, the 8l on 3s lipo is overkill. I was running that setup in my E-firestorm and it was too much torque. I ended up shattering the diff gears after a few bad landings. I've tried a few motor/esc combos in that truck.

1st: Velineon, 7700, 2s lipo - unable to gear down enough - motor got too hot
2nd:Velineon, 8l, 3s lipo - esc would cut out for no reason, eventually one of the motor plugs on the esc broke
3rd: MM, CCBEC, 8l, 3s lipo - insane geared at 20/50 32 pitch. would wheelie at any speed. couldn't drive it at more than half throttle. it would either wheelie or balloon the tires to nearly twice their size.
4th: Sidewinder, 5700, 3s lipo - ESC got way too hot. dropped to a 2s but just not fast enough.
5th: MM, 5700, 3s - perfect geared at 17/87 48 pitch. Completely drivable with good throttle control and will easily pull double backflips on jumps.

The Slash will be limited by the tires so an 8l will be undriveable. Remember: 2wd + small tires = never going straight. :wink: