Bob, how does that TLDI compare to a 4-stroke 50? My bigfoot seems to get pretty lousy mileage at top end speeds, but quite good at hull speed...and extremely good when motor sailing.
On my 06 Merc 50hp Bigfoot I have made 90 miles at WOT in no wind conditions on 22 gals. I get 8 mpg at 8 mph and 10 to 14 mpg at 5 mph (it depends on which way the wind is blowing and how much)