Jammin CRT - middle diff

[lincpimp]

Personally I would run a 9xl, but it depends on the speed you want. Is it fast enough now for you? A 9xl on 5s lipo with the appropriate gearing will easily do 40mph. A 10xl may run slightly cooler, but not as fast. I geanerally try to keep the motor rpm at around 35k. That seems to be the best place for the xl motors, much less and the gearing puts too much stress on the motor trying to get to 40mph, and much more and the motor produces too much heat. Feigaos are very picky about gearing and voltage, they have a small window to work properly. I like to have my vehicles to run at 40mph, and max motor speed of 35k rpm lets me do that with reasonable gearing.

Have you used this yet:http://scriptasylum.com/rc_speed/_top_speed.html it will allow you to play with combos in oreder to find the best match of equipment.