My Duramax runs circles around my old 87 6.9 no smoke or oil consumption . The torque curve is around 1500 rpms. thats where it likes to pull and so quiet. Nice smoth shift on the Allison and the tow haul feature is a + you can go down hills hit the button and it sences the load and shifts down to 4 th gear and acts like a retarder with little or no brake reqiered.The payload is great to with the 2500HD and I love the 4 doors with the family and the Arima.
Bear