The 5 mm was just an estimate based on my own car, but it might haven been 10 mm. It's difficult to remember how it sat with the standard beam as that is a few years ago now.

The 32 mm is based on a calculation that has a few estimates in there, like the weight and the distances. Especially the distance for the spring is difficult. I have taken the center of the spring, but effectively the spring might act more at the rear (closer to the wheel) than at the center of the spring. If that is the case the difference between standard and 6 degree beam becomes less.

In the below picture (of a BMW E30 rear suspension) you can see what distances I mean. To get the motion ratio you need to divide the length of the light blue line by the length of the green line. When the inner pivot is moved these lengths change, even though the outer pivot is still in the same place.