Any time you improve and increase air flow in your engine, whether through intake or exhaust improvements, it is likely you will also need to increase fuel flow. ProMAX Adjustable Fuel Pressure Regulators give you the easy ability to tune your cars fuel pressure to fit the modifications you've made.
Computer chips (remapped EPROM's) can control the pulse action of the injectors but only an adjustable fuel pressure regulator can regulate the volume of fuel going to the injectors.

Part #PM4509 replaces Bosch #0.280.160.286 and 0.280.160.287 and Part #PM4037 replaces Bosch #0.280.160.226 and 0.280.160.227.

The standard Fuel Pressure regulator is rated to 2.5 bar at idle. If additional performance is required (using the standard injectors), it is usually necessary to increase fuel pressure if using higher boost. This is due to reaching the maximum capacity of the injectors at higher RPM - which would otherwise cause the engine to run lean (with too high an Air/ Fuel ratio). An adjustable FPR has the advantage of remaining useable even after changing to higher flow injectors.