Roughly, how much gas mileage / speed difference would one get with say a 115etec vs a 150etec vs a 200ho etec. I'm looking at a new Hurricane deck boat, 19ft and am interested in having an etec mounted on back. They come with Yamaha 115 4stroke; but I want a simpler, lighter, faster solution. And I am interested in the etecs. Thanks for any help in making this decision. Gary