Most issues I have experienced with noticable differences between set speed and actual speed were caused by high engine load and high boat trim (the amount of weight and the distribution of it in the boat).  Testing for this problem can be done by checking for differences between set speed and actual speed when the boat is run with a very light load and again while the boat is using full ballast weight and the wedge.  The issue often occurs when a larger pitch standard prop or speed prop is used on a boat with too much weight.  The solution would be using a lower pitch high altitude torque prop. 

The recommended HA torque prop for the 2024 Axis T220 with the M5DI engine is Malibu PN 3541919, OJ 1919 Wake Pro V4 15"x13".  Loads caused by using full ballast, the wedge, and large crew/equipment weight may be too high for the standard Acme 2249 prop or the Acme 2277 speed prop on your boat in the conditions you are using it.

I'm on a river, but it has very little currwnt/wind to affect speed. My 2020 t22 I never had this issue 

Does any one run the gx tower down cover on there M220? Or any similar sized boat with gx tower and the tower down cover. Just looking to see what you think of the fit and how well it is against water pooling when left outside in the rain.  Cover will be used only when in slip not for trailering. If you have any pictures that woudl help too.

Has been some talk about this. Are you on a lake or river? I think the issue was on river. Don't know answer but you should be able to search and find it.

Is anyone having issues with their cruise control. I have 2024 T220 m5 motor and the cruise is all messed up. If I set my cruise setpoint at 22mph I'm actually going 23.5-24 according to GPS, to obtain 22mph I have to set cruise at 20.6mph. I know you can adjust actual speed on paddle wheel but that's not the issue, it's the setpoint speed, almost like calibration is wrong in setting to control throttle. Does anyone have any ideas, the dealer is checking g with malibu but so far nothing..