15' Grumman Jonboat. 16" transom height. 46" across the bottom at the transom. Normal everything else. I've been thinking the medium SR but the after seeing the video of that 94mph boat in Thailand, this 62 old idjit wants to go fast, so I'm thinking maybe the large SR with a 22HP motor. I know I won't hit 94 mph but want to feel the wind in my hair. I want some thrills thru the 4 inch water and have some fun. More HP, more fun. My question is about the over all handling of the big boy. I'm trying to weigh if the big boy would be fun, but just that much more constant work cause of the more weight to steer, maneuver etc that it would take away from the thrill of the extra speed. Also 2 or 3 guys ( beefy old farts) with too many decoys and crap, I could use the extra HP. So, with all that said, how much more effort is it to handle the Big Boy vs the Medium Boy? Also I am assuming I need the regular 80" shaft?