hei kmb, i am of course aware of that, still, if you look only at the "pressure side" feeding bearings, etc, it's notable how much wider the 500 rotor is. IMHO, the fact that the pressure side in the 750 is fed from the oil tank and in the 500 it sucks from the sump, would make very little difference to the volume per pump revolution. Just a side conversation/food for thought.