Some folks just have to tell you something you didn't know, even if it is nonsense.
Not likely. NMMA allows +/- 10%. An extra 17HP would exceed that.
Any given Yammy 150, on a Dynamometer, would deliver something between 135 and 165HP to be legally called a 150. Most of them would be very close to 150HP.
The same is true, of course, of any 150HP outboard made after the mid 80s, by any brand.