250 xs power

[RidgeRunner]

250 EFI Current engine is a 3.0L burns 32+/-GPH WOT. WOT is 55 to 60 with a load. All around average fuel mileage cruising and such is approx 1.5 to 2MPG.
The 225 Opti also a 3.0L on a 23' Whaler Outrage averages 3.0 MPG. Heavier boat by a long shot and not near as efficient in the water as the V-20.
At WOT I expect very little gain but the idle and midrange (cruising speed) is where the Optimax shines. I would expect it to be as good as the 4-strokes in the same hp. I know Joe in Miami installed a 150 Optimax on his cuddy but have not heard of his mileage. A lot of guys seem to be going with the E-tec which is also a direct injected 2-stroke albeit much more quiet. What do you think Spare, Skool, Ferm, Genie Aye?
Will I see 4MPG?