No matter where any of the settings are set, you will receive the same mileage when staying out of it and just cruising.
They do not change the amount of fuel 4 cylinders totaling 1.6L of displacement needs to maintain a certain rpm.
With my Rover pump set up for full on gang-bang-o-rama, I can cruise 95-100km/h in 5th by barely resting my foot on the go-go pedal. About 1/8 of its travel to maintain this speed. Up hill? I gotta put down another 1/16th of an inch..
You could put a Bosch VE 14mm injection pump on there (hypothetically speaking), cruising it would still net you the same economy. Being that there is no throttle plate (I assume you know this
) RPMS are directly linked to the amount of fuel injected. Inject more fuel they go up, let off and coast in gear little to no fuel is injected.
This is why diesels generally see no change in mileage with heavy performance gains. Direct Injected actually sees benefit to larger injectors in more ways than just power. They also gain efficiency, thus improving miles per gallon. The ability to inject fuel quicker in the injection process makes more use of the fuel injected.
The little pin that rides on the boost pin is only used when load fueling. Here is a scenario, you mash the go-go at 1450RPM. Wit ha properly setup pump, it will not blow black smoke. It will however raise the rpm's as quickly as it can with no boost present. Effectively an NA diesel with a huge exhaust restriction. As the boost rises (we'll go 1 psi at a time for easy learning) each psi of boost pressure pushes the boost pin down in its bore x amount of movement. The little pin that rides against it is being pushed by the internal throttle, but is being restricted because the boost pin has not moved down allowing it to move yet. Boost pin moves down psi by psi, and millimeter by millimeter the internal throttle is allowed to increase because the small pin riding the boost pin has moved out of its way on the slope and is now allowing fueling per boost. You set the amount of on boost fueling by turning the boost pin to whatever slope you desire. I would leave it at the steepest setting, because in the end.. it all depends on your right foot.
The screw on the very top, the "smoke screw" does the job of off boost fueling coupled half-and-half with the star-wheel. If you have turned your star-wheel down so that the top pin just now only touches it the top of the boost pin then you have effectively added more fuel before boost picks up.
I generally bottom out my star-wheels, use an AAZ boost pin spring (half as tough as the 1.6 pins.. pushes down with less boost.. more fuel QUICKER!), and have the smoke screw just touching the top for ease of adjustment later.