[blykins]

They are certainly for high performance applications.....being able to withstand a continuous 600 lb-ft of torque. You could use them in a race car as well....but every box has its limits. Due to the machining on the gear cones, the sizes of the gears themselves (you need some big gears and larger diameter shafts to withstand that much power), and the quality of some of the other components, they just don't like the revs.