plowboy, I'm not sure your concern for the RPM of the Cummins engine is warranted. I don't think you will cut the life of the engine by running it at the factory RPM setting. As for the rest of the machine, it will probably be pretty sensitive to the engine speed setting. If you email me I will give you the n of a person who will set the governor in your injection pump up for optimal combine performance and adjust the HP to what you want. If you set the HP down from the rated spec, that should do more to help engine longevity than lowering the RPM, but I doubt it is worth the capacity loss.