I have a 19' chaparral runabout with the 220hp alpha one mpi. The boat came with a three blade 21p aluminum propeller and I can run mid 40s when I'm solo and the boat will Rev to 5200rpm. I purchased an aluminum dual geometry 4 blade 21p and it slowed my rpms down to a straining 4200, so I returned it and got a 4 blade 19p. It runs a bit slower but is definitely better when running heavy loads but again my rpms get to about 5200. I want something that'll give me just a little bit more top end and keep my rpms below 5k at WOT. will a 3 blade 21p stainless lower my rpms because it grabs better or will it potentially increase rpms because it's thinner? Or should I get a 23p? All help is welcomed, thank you.