On regular 2 toon boat a 115 will about max HP and run in low to mid 30's, a tritoon is a whole different animal, I have a Bennington tritoon with 150 Yamaha it will run in the 40's and turns like a runabout. The boat is rated for a 250 but it really doesn't need that much HP. I hit 40 mph in it with 9 adults onboard and it rides smoother than most runabouts I've been on.