So I have a 96 Chaparral 1930ss with a 4.3lx merc. I have had this boat for 3 years and been out more than 10x a year. I have tested WOT more times than I can count and have a really good feel for the rpms on the boat. I have a 3 blade 21"p propeller and have always turned 4800 rpms at the absolute max unless I put on my 17" 4 blade. I replaced the hub of my 3 blade propeller mentioned above and because I noticed a small crack when I was swapping props a few weeks ago. Last time I went out on the lake I was driving as always and went for WOT. Luckily I looked down soon after planing because I was exceeding 5k rpm and still had throttle left. I am not crazy and I have done nothing else to the boat other than change the hub of the propeller. I was actually considering a full tuneup because the boat has not been running optimally this season. Has anyone else ever seen or heard of anything like this. I would suspect a faulty tach but my top speed was faster too. I'm fine with having extra tbrottle I just have to watch my rpms much more closely now.