today i went to a 15 from a 13 pitch prop. got a really good deal! called arount first and each boat shop said jump all over it. my boat has a 40 hp mariner on it, w/ a 13 pitch prop. I got a 15 pitch for 50 bucks. from what i understand i will lose bout 300 to 500 rpm's on the hole shot but will make it up on the top end w/ no rpm loss there thus gaining 4 to 5 mph. what do y'all think?