I just installed the lv2 yellow motor and gear. I had to take apart the whole drivetrain. This took a little while, as did trying to push the heat sink in and reatach the motor. It was a little complicated taking apart the driveshaft and everything. Also, a guy at the shack said that I need the xmods batteries to get full power. Another thing- attach the heat sink to the engine before you screw the engine in...
Know what you're getting into!