For all of you Zbox tweakers I thought I might share something I discovered while using Zbox ( club boat has Zero Off now, 2017 was the last year I used Zbox).
Had every aspect of the hardware in order (power supply, return spring, pucks etc).
Just for the heck of it I set all the background settings to 0 and drove the boat through the course without a skier. I totally expected a constant speed through the pass but that was far from the case.
Can't recall the details now but rpms (and of course speed) was slowly shifting up and down, somewhat in line with the notorious fast entrance and a slow buoy #2 followed by a boat that runs fast from buoy 2 to 4. So there is some inherent programming that is the cause of this behaviour.
Can't remember which version but it was the latest in 2017.