FDF's rear control arms allow you to achieve correct rear camber and toe on your car. The factory BMW suspension has a very aggressive camber gain through compression - this is extremely noticeable when lowered. When you lower your vehicle, it naturally adds more camber - these upper arms allow you to correct that rear camber to give you more grip. FDF's rear arms also eliminate deflection found in the stock bushings. Instead of using rubber, FDF uses 3/4" Teflon lined rod ends.