SuperPro's KIT5239RK is an all-in-one-box rear suspension upgrade that pairs well with our complete front lower control arms or any combination of front axle bushing or bushing/mount/geometry upgrades. This kit is our Motorsport version upgrading several bushings in the kit to a higher durometer material to minimize flex and deflection further improving dynamic alignment and maintaining a more consistent contact patch. The standard kit (KIT5238RK) does this exceptionally well on street tires and in most track day scenarios. This kit's uprated durometer doesn't product tangible performance benefit until you're utilizing slick or particularly sticky r-compound tires along side other suspension upgrades, aero, etc. This kit upgrades the following bushing locations: Rear Control Arm Upper-Inner Bush Kit Rear Control Arm Upper-Outer Bush Kit Rear Control Arm Lower-Inner Front Bush Kit Rear Control Arm Lower-Front Outer Bush Kit Rear Control Arm Lower-Rear Inner Bush Kit Rear Control Arm Lower-Rear Outer Bush Kit Rear Trailing Arm Front Bush Kit