The 8000RPM part is making me wonder about cavitation. You shouldn't be able to run that high unless you cavitate, certainly not with an OEM impeller (and stock ECU). At 8000 you are hitting the factory rev limiter:
View attachment 38161
That can happen during hole shot, when you can hit the rev limiter a couple of times, but once you get going your boat should not rev past about 7700-7800 max.
Keep in mind, even with ribbon delete many 190s will not go that high (7800). If you are consistently running at 8000, something is not right.
From your picture - the impeller and wear ring looks okay, at least there is nothing obvious. But I think you will have to pull the impeller to really look at it. And then inspect the sealant around the wear ring.
Is 44mph measured by GPS or boat speedo? If it is GPS, and you run 44mph consistently, I would say you are not very far off from your boat's full potential!
Except that you do not want to be running on the limiter. If I were you I would try to find the source of cavitation (or impeller slippage). If it is the boat's speedo's 44 max - than you have even more reason to explore it further because you should be running faster speeds, probably around 44mph GPS, at 8000RPM.
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