A'PEXi Adjustable Fuel Pressure Regulator - Stock fuel pressure often does not allow upgraded injectors to perform at maximum efficiency. By upgrading the fuel pressure regulator, the user can adjust the fuel pressure to optimal levels. Upgrading the fuel pressure regulator on factory size injectors will also allow the injectors to perform at an improved level. The easy to use adjustable screw on top of the regulator can accommodate a wide range of tuning necessities.