I chose to buy stock length because I did not want to fool with the geometry of my bike, something I know very little about.   Also, I use my Vulcan as a touring bike with passenger, so I did not think it advisable to sacrifice clearance.

The settings on the shocks are simple to change.   There is an enclosed sickle-shaped tool for the spring preload, which hooks into notches on the cam.   Damping is adjusted with a small plastic Allen wrench (supplied), shaped like a tiny shock absorber.   Cute.

For 2-up riding, I found it best to use spring setting 2 and damping 3. Solo, I take the damping down to 2.   Higher settings provided no advantage.

The ride is excellent.   The 418 shocks takes out most bumps on the road, and the rear end suddenly feels much smoother.   Now I feel the handlebar and fork much more, especially their inadequacies, because there is no more stomping, bumping, and flexing coming from the rear suspension.   Long, sweeping turns with bumps in them are much easier now.   The rear tire seems to be glued to the road all of a sudden.

The suspension does not feel stiffer, nor does it feel softer.   The best way to describe it is -- you feel like somebody secretly repaved the road while you were changing shocks, and took all the bumps out.   On US 129 in western North Carolina, there are some stretches where the road was repaired with big "band-aids" of asphalt, which are raised about 1/2" above the rest of the road.   Last May I rode that stretch with the stock shocks and did a nasty dance whenever the edge of the band-aids was in line with my travel.   On the 418's, the problem does not exist.   Also, rain grooves used to bother me a lot on the highway, while I can ignore them now. I noticed too that even with the stock seat on the bike, I don't tire of riding as easily because I don't get bounced up and down anymore.

Feeling the shortcomings of the fork more clearly now, I plan to get progressive fork springs installed also.

My overall rating of the Progressive 418 shocks:   excellent, in spite of the high price.   Probably the best investment I have made for changing my 1500D from a Boulevard cruiser into a comfortable touring bike.