Since I have been on a fin mod theme here at 23B I started looking up some more shots and links to how people are changing their fins.
The Greenough mods shot by Warren Pfeiffer.
Greenough cut down the length of the fins, thinned the ribs and changed the shape of the straps to fit his feet and ankles.
Here is another link to Swaylocks where they have spent years discussing fin mods.
I did another post on fins a while back about some different kinds of fins and the strengths and weaknesses of each.