18 HP B&S In a 618 Grasshopper ? Can a 18 HP B&S be put in a 618 Grasshopper as they never came with one ! Came with the junk Kohler OHC 18HP engine ! One of the worst engines have ever seen ! Thank God they don't make them any more! A Grasshopper mechanic told me it could not be done and I beg to different ! Any comments on this?