These bushings firm up the rear differential subframe with respect to the chassis of the car, reducing or eliminating the dreaded rear diff thump on hard acceleration. The polyurethane Kartboy pieces insert into the stock bushings to make a firmer connection of the subframe to the chassis. The result is better control of the rear differential and rear suspension under cornering, acceleration, and braking.
Available in two different hardnesses -- Comfort is firm but not brutal, while Race is pretty darned hard.
Mach V Matt says: "Great addition if you don't mind a little more NVH. Pretty easy install"
Kit includes six bushings, four of which will be used for a given car. Fits all 2002-2007 Impreza/WRX/STi/Forester.