Increase fuel flow volume from the fuel pump to the fuel rail by replacing your vehicle's stock restrictive fuel rail fitting, reducing pressure drop and increasing performance. Unfortunately, we have seen too many people take their stock rail fitting and simply drill it out. While this may work in the short term, because you are removing the surface, it will rust, and this rust will deposit into the valves of the injectors, causing failure. These rail fittings are sold individually, however it is HIGHLY recommended to replace both fittings (one on each rail).