For anyone out there thats trying to get more out of there XMOD then look no further than the Megatech modified motors for the mini z's. I went and picked one up from my LHS (checkered flag here in st louis) and installed it yesterday. I dont know how well the NML and stage 10 motors are but this little baby has gotta be at least a stage 4.
It's whole lot faster than any of the stage 2 motors by being rated as a high torque high speed motor. Only cost me 20 bucks and then another 7 bucks for some new pinion gears.
Just clip one of the connectors off your old motor and install it on the new one. the heat sink fits and the little yellow brace on the back fits as well. And you can order one of these from Tower Hobbies , they offer three types, high torque, high speed, and high torque / high speed.