The stock pieces are designed to work for a stock car under normal type conditions. Under heavy braking, the front control arm main pivot flexes, causing changes to your alignment. After upgrades like stickier tires, brakes or stiffer suspension bushings, the OEM brace doesn't cut it when pushing your car to the limits. The PERRIN control arm braces are CNC machined from 6061 Aluminum making these parts much stiffer than the stock part.