You sure do need a 19p prop.2011 Lowe 17HP Merc 90 Opti MG 75
Love my 17HP cause it fits in the garage. I get about 30mph at 4000 rpm which is the best overall cruise speed. I'm running a R series PowerTech Stainless 3 blade 21P prop and the engine is in the third set of mounting holes from the top. I can't trim up very much because of the dreaded Lowe porpoise so I can't get past around 5100 rpm. I've heard about welding on some tabs but don't want to do that. If you have a 17HP and are getting better numbers than this please let us know what prop you're running. If I could trim up the rpm would go up and so would the speed but around 40 to 41 mph at around 5100 rpm it starts jumping up and down like crazy. All in all I love the boat and knock on wood the Opti hasn't given a moments problem.Attachment 348211