I need a new motor for a 21' Sun Tracker pontoon with 24" tubes. It had a 60 HP Mercury Bigfoot on it. Can anyone tell me the estimated projected top speed with a 50 HP, 60 HP, 70 HP and 90 HP?The local Honda dealer commented the 50 HP was probably the best choice because as the HP goes up, so does the weight resulting in only marginal increase in speed. I'd like some data to support this.Thanks in advance. This is an excellent forum.