I am trying to figure out some of the differences between these two machines. Wheel Motor Specs: http://www.parker.com/literature/Hydraulic Pump & Motor/_TG_Series.pdf The SuperZ 2013 has Parker TG0310 wheel motors which spin a 24" tire at a RPM of 303 and a torque of 924. This has Hydro-Gear PY 21cc Pumps. http://www.hydro-gear.com/main/products/py-pump-with-aux The Super Z 2013 HD has Parker TG0280 which spin a 26" at a RPM of 334 and a torque of 796. This has Sauer Danfoss DDC-20 Pumps. http://www.sauer-danfoss.com/stellent/groups/publications/documents/product_literature/l1104976.pdf Other than a different suspension seat I can't find any other physical differences between the machines. Are the Sauer Danfoss pumps really that much better that hustler is willing to extend the warrenty an additional 1 year on parts just because of a different pump?