Hi all, i'm new to the board.
I think a high-5 prop is best as a skiing prop because it has large blade area and a great hole shot for pulling skiers up. But as an ultimate top speed prop, a cleaver surface-piercing prop is best. Mercury racing do them, but these are priced accordingly.
If you speak to David at Steel Developments, he can advise on the best prop. They do a race - prep service which will make your prop into a cleaver style for a LOT less £££ than to buy a new mercury cleaver. Running at this height to will mean your water pickups are out of the water. As Pete7 said, Chris Lewis is the man to speak to because me can either fit you a nose cone with low water pickups or can mount a pickup on the hull and pipe it into the engine.
You may also need a transom jack as the standard engine mounts won't have enough lift .
Unfortunately, running a surface-piercing prop isnt all good news. It has less grip than a normal prop so may not be able to pull a skier. Steel developments sell stainless steel props at great prices which could then be made to run as a surface-piercing prop and leave your mirage for skiing and for use when the boat is loaded up.
It would be good to ask owners with outboards running surface piercing props to get their views on the handling of the boat and its performance.
If you still want more speed, steel developments do a hull coating which reduces the drag and increases speed. I bought some at RIBex for my Ribtec 585 and will tell you the performance differences once I have applied it and tested.
There are two American companies which do lots of products for making outboards go faster - http://www.land-and-sea.com
A surface-piercing prop when run at the correct height should give better performance and a great engine sound because the exhaust is half out of the water when the boat is on the plane.
I hope this has been some help. If you have any questions, please email me and I hope i will be able to answer them!
Ralph Payne (Age 15)