I have a 21'6" renegade open bow(similar to an ultra). It is a big heavy family style boat. Even after having a fresh wear ring installed and the leading edge of the impeller detailed I am still experiencing a lot of cavitation. I have a legend pump with an A impeller and a place diverter. The pump is set back with the hand hole completely outside the boat. I have read that not having a ride plate on a setback pump may cause this. Any suggestions?