It's more of a duty cycle thing. High speed cat's don't usually run wot for much time. Big v's with big torque motors might see more wot stick time. Put them behind 500-700's and with some oil changes you could go literally hundreds of hours before major servicing, but you don't want to wait until they break! There is a real big spread of applications out there so it's almost a guess on their part to give a quick answer.