Opie, What pitch and diameter are you spinning now and at what rpm? Are you looking for all out speed or skiing? My first boat was a 16 foot Avenger with a 140 merc. It worked really good with a 23" clopper ( I want to say 13 1/2 " dia.). It would do a little over 60 mph @ 5800 rpm and pulled skiers out of the water all day long.