The Motorsport version of this kit steps the durometer of the material up from 80A in the standard kit to 90A. Due to the bushings location under the rear seats the higher durometer can bring more road and tire noise into the cabin as well as some additional impact harshness. The higher durometer material reduces deflection of the bushing under changing loads resulting in more consistent rear suspension geometry and greater rear end grip in extreme and motorsport use. Trailing arm bushes stabilize the movement of the arms to ensure the correct geometry is maintained in all situations. Worn or rubber bushes in these locations lead to dynamic changes in wheel alignment that effect the handling of a vehicle as well as the tire life. SuperPro Bushings solve this issue and are the perfect repair or repair upgrade solution.