2007 Grizzly 1754, 25hp 4 stroke. Need help upgrading motors

[saltfisher]

My dad has a 2007 1754 side console tracker grizzly. Beileve the hull weight is about 740lbs give or take. Pretty much the dealer he went to talked him into the 25hp 4 stroke telling him that its enough motor, and should do close to 30mph. Well my dad got it, and I told him a 25 was way to small. He found out the hard way, and with me and him it cant get better then 21-22mph on GPS with basiclly no load in the boat. usually we see about 19-20mph. Cant even really get on plane, as the bow sticks up while running. Lucky the lakes around here are not to big so it still only takes 10 minutes to get accross the lake. Not like 30 seconds in my bass boat with a 150 merc. Anyways... He wants to now upgrade and wished he went bigger to begin with. He LOVES the fuel economy with the 25 4stroke, and wants to get either a 40 4stroke, 50 4stroke, or the 50 2stroke that merc still makes. So how much fuel will each of those motors take compared to the 25 4stroke he has on now? Also what kind of speed difference are we looking at? The reason he still didnt get rid of that 25 4stroke is that he can run all day on a gallon of gas. To me gas doesnt matter as long as my boat moves 60+mph. I can go through 15 gallons in a day. He is the complete opposite. Anyone help? He will probably be getting a mercury again since his boat is rigged for one. he is thinking of selling his 2007 25 on now, and getting something bigger but a few years older to make up for price difference. That way he doesnt have to add around $2-3k just to get a few more hp.

[paxpress]

What state are you in?  If your close to me, my dealer can answer your questions and get you in the right direction 

[saltfisher]

Lancaster PA

[paxpress]

PM sent 

[saltfisher]

I dont think he is getting the 40 horse now because when we went to look at it we found quite a few scratches on the cover. He said if he is buying a new motor it has to look new also. Not used. It was dirty, and had quite a few scratches on the motor cover. Not a huge deal, and wouldnt bother me, but its his choice.