Upgrading my 2006 Malibu Response LXI to Zbox was super easy. Dialing it in is a whole different deal. Just like my experience with Stargazer I found that prior to entering the course the boat would surge: most of the time. Sometimes it would surge in the course and continue all the way to disengage. Long story short, I chased a bad ground issue and a sporadic depth finder alarm (that still triggers even though I've clipped the depth finder power wire from the ignition), but the fix, so far, was changing the CR/CS value from default (1600?). Initially, I ran the Auto Calc for CR/CS and it set it at 2450. This produced some great time checks with all perfect segments, but then it surged about 400 rpm mid course. I then spoke with PP and they recommended running about a 1940 value, but tune this by accelerating up to speed and pay attention to how the boat takes control. It should not accelerate or decelerate upon engagement. Ultimately I settled on 1910. I ran some speed checks and then skied 10 passes with never more than a +/- 02 split, but most were 00 one or two .01's.
Hope this helps someone.
Also, in my discussions with PP I asked if they would bring back their Pregate speed adjustment to match REV. R of ZO. I just got an email back saying they should have a rev. by January 2013.