Upgrade kits are for customers that already have the VMP no-grind style FEAD system that came with there Odin or Loki supercharger kit. This kit provides additionally pulleys and an upgraded tensioner to accommodate 10-rib style belts along with a new SFI approved ATI balancer designed specifically for VMP. Afraid of belt slip? Convert your 6-Rib Odin/Loki kit to an 10-Rib belt drive system! With more ribs on your drive system, there is more surface area to help make belt slip a thing of the past. Not only are you adding more ribs, but this kit will also come with the VMP Heavy Duty Tensioner for more belt tension as well.