The OEM fuel pressure regulator is 3.8 Bar (55.86psi). This is the amount of fuel pressure that is maintained in the fuel rail. In high power applications, when the boost pressure and power is increased, a drop in fuel pressure can occur causing a lean condition with the OEM 3.8 Bar regulator. The Evolution Motorsports 5 BAR Fuel Pressure Regulator (FPR) by Bosch will keep 5.0 Bar (73.5psi) of fuel pressure in the fuel rail to eliminate loss in rail pressure while under full acceleration.