If you want to go fast around trees get the KDX. If you want to go really fast through trees get the KX and modify it. If you want to go really fast and fly high get the KX. If you want to feel like a bag of chips after a round on the MX track get the KDX.:thumb:
For more informidable information do a DRN search on this topic.
kx's are designed for motocross and produce more horsepower at mid to high rpms. kdx's are designed for trails and produce more torque at low to mid rpms. the kdx is better for riding in trails and it can be used for racing. the kx is better for racing but more of a hassle than the kdx on trails(in my opinion). the choice of mx or enduro is dependant on your style of riding. if you ride in the high revs and like to jump gor for a kx. if you ride in the low revs and like a smoother ride go for a kdx.