The 9L would be the best for running up to 12 cells. Somebody on the forum was using a 380c 6L in an MT2. I forgot who, but I think he liked the performance.

Personally I think any 380 will be pretty underpowered, even a 380-L. The 9L should work well, I used one in my RC10GT for a while on 12 cells and it was VERY fast. Realistically too much power for 2WD but oh so fun.

A 540-12S would work well as well, would be lighter and more controllable.

380-l is more than fine for a 2wd light car, i wouldn't use it in a 4wd mt2