The RST has an adjuster inside the electromagnetic fuel pressure actuator (behind a blanking screw. The adjuster is an allen key) on the side of the metering unit which affects full throttle enrichment. I would leave this one alone unless you know what you are doing with it as it will affect your on boost fueling and melt your engine if you go the wrong way. You will need an aif to fuel monitor (wide band lambda sensor).

It also has a base fuel pressure adjuster inside the fuel pressure regulator. You have to remove the fuel return pipe to get to it and you need an allen key to adjust it. Base fuel pressure setting is 5.7 to 6 BAR.