This is a rear axle bar upgrade for the CTS-V platform. By now you all know the 2009+ cars came with different diameter axle bars so the axles would wrap up and release at different rates, allowing the wheels to release at different times eliminating wheelhop. The factory axles on the 2004-2007 were made the same diameter and wrap up and release at the same rate resulting in wheel hop. If the suspension were set up properly this would not happen, but through our extensive testing, we have created a very cost effective solution to this problem. When making the axle bars we decided to make the shorter axle the thick one and the longer one skinny. This was determined by basic engineering principles that state a longer bar will twist more then a shorter one (ever use a long extension on a breaker bar ?). The axle bar upgrade includes both axle bars, powdercoated black and comes with boots, clamps and grease.