I could not find much about this project on ADV prior to starting. Did find some info on the F650 which helped somewhat. Here is a specific F800GS project on changing the rear shock spring. I wanted my new F800GS to be about an inch lower so ordered in the Hyperpro shock spring. Here is what I ran into. First spring is .150 smaller in diameter, it will fit ,but requires you to bevel the spring edges on the internal diameter on each end so that it will fit over the lower and upper spring centering washers. Not a big deal but definitely made for the F650GS or S and NOT the F800GS. Changing out the springs was not too bad once you have a good spring compressor. I used the Harbor Freight compressor shown here. To those who might use it in the future, cost is $12 BUT it is made for larger car coil springs and you will have to grind down the ears for clearance on the BMW shock. Works ok but not the best. Once compressed you can then simply slide down the preload assembly exposing a small retaining wire that rides in a grove on the shock body and the inner preload assembly sleeve rides up on it to capture it in place and lock the assembly. Once the stock spring is off, putting on the new spring is easy since it is one inch shorter and you don't need a spring compresser with it. As another point of information. Eye to eye, the stock shock is 17". A shock that is 16.4" on these same deminsions would have been perfect for my size and inseam. Also found that with the Hyperpro spring the bikes rear sag is quite a bit more since this spring is a "rising rate" spring and not a straight would spring like the stock. This resulted in the bike being too low and the swing arm was almost straight horizontal when sitting on the bike. So I machined an aluminum collar .400 thick and placed it under the lower spring locating washer. Result is the bike now is lowered only 1 inch with suites me best with a 32" inseam and 170 lbs. I then slid the forks up in the triple tree about an inch and the bike sits level and I feel much more in control being able to flat foot the bike. Another point, the side stand now is "just right" and the bike has about a 10 degree tilt. So this conversion solved excessive lean angle as well. Center stand works fine too. Have not had the opportunity to ride yet (29 degrees with ice here) but will post more when I do. here are some pictures of the finished project. Special aluminum collar machined to raise shock spring. Side view of shock.. Total time on this project was about four hours, most of which was spent making the aluminum collar on my lathe.