Hello all, I got a 1991 Mercury XR4 serial number 0D038009. Had the boat out on the lake today and I don’t normally hammer WOT all over the place, but opened it up and only got 4300 rpms or so at WOT. It should be more like 5500-5800 if I’m not wrong. Bought a new 26 tempest prop for it this year after having to replace the old small (1.78) lower unit with a SEI 1.87 this year. Used mercury prop calculator and got 25/26 pitch calculated for 64 mph at 5500 rpm. Boat is a 1991 Ebbtide Dyna Trak 181. Weighs 1150 dry, 26 gal tank, calculated 600 people n gear. Got a total weight of 2200 lbs. Merc recommended 25 or 26 tempest. Bought the 26 and here we are. Had a heavy tournament load (about 800lbs or so people n gear) but didn’t think that extra 200 lbs would bring the rpm down so much. Would that extra weight affect it that much? Or is something else wrong with it that I’m not seeing. To me it doesn’t add up but figured I let the pros see if they find something. Thanks everyone