The K-PAX Racing rear subframe allows for a full spherical bearing conversion and has corrected a lot of the ride and NVH compromises the S60 had when it rolled out of the factory. Moving the rear differential up allows for reduced angles on the axles, which can contribute to roll resistance in a non-linear fashion (not to mention reduce component lifetime). The rear differential housing is fabricated in house and stuffed with an Emco limited slip and either a 3.752 or 3.974 final drive, with the front differential remaining open per the rules. As a result of the front weight bias and open front diff, the S60 uses a huge rear sway bar and no front sway bar as wheelspin was excessive with the front bar installed. Easily accessed connection points for the control arms allow for quick and easy adjustment during practice and test sessions, and the integral jack point is a must with a car with extensive underbody work. The brick located near the differential is there for weight ballast.