the fuel pressure is adjusted via the fuel pressure regulator on the side of the metering unit it needs to be removed then unscrew the blanking screw and adjust the grub screw using a allen key DO NOT DO THIS URSELF!!!!! as u will have no idea if u have made it overfuel, this is done when the car is on the rollin road the operator checks the air/fuel ratio then adjusts the pressure regulator to suit

personally i would only let a tuner who knows the bosch ke jet mechanical fuel intection system very well near it