depends on which motor, the carbed will get 2-3 mpg the opti, probably 4-5.
this is on a cuddy, center console would be a little different.
cruise between 28-32. wot 38-42
load and conditions make a BIG difference, as well as the prop.
if your wanting to go fast with a load, might want to look at a 200. it's easier to run a 200 at 3/4 than a 150 at wot.
the last 150 i put on was a 4 stroke, totally different animal. i get 4.5 mpg at 32 mph, top end is 42mph and drops to 3.5mpg. i considered an opti, but to get 4S performance out of a 2S, you have to run it right on the edge of imploding. i opted for the simplicity and ease of maintenance of the 4stroke. this motor kinda reminds me the old dodge slant 6, not the fastest or the sexiest , but hopefully the toughest.
i've got 140 hours on so far and love it.