Set your pp at a wakeboard speed you use. Turn it on and then start driving. Take your gps with you and get your speed via that. There is an adjustment on the pp module that will increase or decrease the actual speed til the speed matches the gps. It needs to be adjusted in the "calibration" mode You again will want to use the speed you wakeboard at most for the calibration. If you don' wakeboard that often still pick a speed under 28mph but above 18mph.
I don't recall the exact button operation on how to get to the calibration screen, but it can only be accessed if i recall correctly while the pp is engaged...........so you will have to check the pp website. It is very simple and straight forward.
The speed adjustments on your dashboard are for your factory MC speedos. They do nothing for the pp. All the calibration is done through the PP module and the buttons on its screen.
2000 X-Star, 3000lbs ballast, LTR 330, Acme 1235 14.5X14.25prop.