We used our Z box this weekend for the first time on our 2003 SN196, Already had stargazer, so very easy to fit, removed the timer, mapped our 2 courses checked the baselines and skied, Wow just saved £8K! no longer need to upgrade our boat, it worked very well, no more racing through the gate 1.5KMH faster, it gave 16.97 pass after pass, and all the split times were within 2 thousanths of actual. And it feels just like Zero off.
If you havent bought this upgrade go and get it now. And if you are thinking of upgrading your boat save your cash for something else.