To convert 1998 15hp to 18hp, is all that is necessary is 60mm pistons, bore cylinder, gaskets and replace the throttle cam?<br /><br />Anything else to "boost it" that wouldn't greatly deminish engine life?<br /><br />Maybe a better question is where is a good source for good used 18hp?<br /><br />Thanks!<br /><br />Eddy
