I'm running a set of Pelican 1600 cases, their huge, 91L volume between the 2 cases, on my F650GS 39.25" wide. One my F800GS they should be just under 41" wide. Most people seem to be running the 1550 cases, but for a case that really isn't much bigger, the 1600 offers a lot more room. 1600 is 4" wider, 3" longer and 0.5" deeper, but works out to a sizable space difference: 32L in a 1550 vs 45L in a 1600. I hung them so that the extra length is down low, and while I could see the extra width being a pain if you're riding 2-up, I don't (the girlfriend has her own bike for that), and the extra width is peanuts. then again, I was looking for 1550 cases, and managed to find these 1600's for dirty cheap...beggars can't be choosers, but I wouldn't go back to the smaller size!