I modified the original boosters to extend the full length of the antennas like Daves, and the other commercial ones. I made the parabolic surface out of a plastic jug and then used the parabolic outlines to push the circular shape into the needed parabolic shape. I used aluminum tape to cover both the inside and outside of the booster for maximum reflectivity. I made sure the inside surface was as smooth as possible. I then tested the shape of my antenna boosters with a laser to make sure that no matter where the beam hit, it would reflect to the antenna just as a parabola should.
With my original booster, like the one shown from the original poster of this thread, I got 15,100 feet distance from a nearly ideal location where I was about 200 feet above a river valley giving me clean line of sight for 20 miles. This time I got 16,242 feet from a very flat area next to high voltage power lines where I could not have clean line of sight.
The limit of my distance now is safe battery life. 5km out and back is about as much as is possible without really pushing the battery past the low battery warning.
Here is the video I took: