You basically have to buy new seats. I would recommend a seat with a bit more padding than Cobreau though. Also something to think about, the D doesn't really high speed all that well with the short wheelbase and limited power. You will probably end up going slow and with a 4 point it is a bitch to lean out and look at what you are going over. I had them and ended up going back to the stock belt and now run lapbelts only in the rear.
2009 King of the Hammers
BUCK Wild Racing
Co-driver: Pat Quirk
Rover Tracks www.rovertracks.com
DJ Safety www.djsafety.com
West Coast Rovers www.westcoastrovers.com
Reel Driveline www.reeldriveline.com
Made it further than half of the other guys, but the Hammers won.