I'm contemplating a Euro headlight upgrade in the future and have been interested in this issue. It seems to me that the vacuum setting should be set in the middle of its' range and then the headlights adjusted properly, so that then you would make use of the vacuum hight adjustment to angle the lights up or down as needed. It would seem to me that the most likley scenerior wil be needing to adjust the headlight angle down to compensate for added weight in the rear of the car. It appears that the vacuum adjustments are basically preset step movements over a finite range. If you want to change either end of the range (either up or down) you will need to reset the starting point either lower or higher to allow the extreme ranges to change. Good Luck ,I'll be waching to see how you make out.