Hi Folks - This is my first post, so bear with me if I've done something dumb already. I've searched this site for hours to see if my question might already be answered, but couldn't find anything. Anyhow, here it is. Can anyone tell me why the Kohler M18 in my 1541 is only 15 horsepower according to the owners manual, and 18 horsepower according to the Kohler manual. (And also 18 HP according to the all-knowing local Kohler dealer.) The Cub manual lists the bore, stroke and displacement, which is identical to what's listed in the Kohler M18 manual, only the HP is different. If you can help, thanks in advance.