I'm inclined to agree with 66T on this...my cush drive mod seems to be lasting and likewise I don't want to be putting extra strain through the transmission with hard polyurethane replacement. Having skinned my knuckles fitting polyurethane bushes to to the sub-frames on my Mini Cooper I really regretted it....no give in them at all and a horrible harsh ride. With all that low down grunt you tend to 'torque ' the Tenere along, short shifting through the lower gears....something the standard cush rubber clearly can't handle which is where the mod comes in . Having said all of that the best help you can give your transmission is a well lubricated and perfectly adjusted chain, and change gear smoothly . Chain adjustment makes a huge difference to the way the Tenere rides and must affect the wear on the cush drive rubbers . Too tight and you can feel /sense that harshness coming through....too slack and it feels snatchy and unhappy get it just right and it's bliss!!. Steve