I don't recommend them, the drive is not designed for them and when during the warranty period adding them actually voids the warranty. Merc will not stand behind any claims if they are added.
They also increase lift stress on the transom assembly, again not designed for it.
Any potential improvements are not worth it. I would recommend larger trim tabs or adding the drop wing to them.
1997 2400 SCR
5.7 Vortec / Bravo 2