Stock rubber differential bushings give a disconnected and mushy feel to the car, especially when worn, as the bushing deflects more than it should. You get sloppy steering, vibrations, and poor handling which makes the car feel unstable. These urethane bushings are stiffer than stock rubber and will not deflect as much. The car feels more planted and confidence-inspiring. And a lifetime warranty means you'll likely never have to pay for another bushing ever again!