Far as I can tell, someone wrote:
I test drove a 1985 Mark Twain 19' bow rider with a 228hp Mercruiser I/O.
It have plenty of quiet/smooth power, but I heard there might be something I
can attach to the outdrive to get the boat level sooner (at a lower speed.)
Does the add on wings or flaps work?

I've read reports from many different people, and most all have said
they do work... to varying degrees.

Yes, they do get you up on plane faster.
Yes, they do limit cavitation somewhat.
On -some- boats, you might lose a mile per hour or two off your top
speed, or you may gain a bit.
For fifty bucks, it's a pretty good investment.

Look at http://www.sesport.com/
and
http://www.davisnet.com/marine/produ....asp?pnum=0440