There is another solution to the top box. Cosmopolitan motors in Hatfielld, PA sells a topbox made by Shad. They import them directly from China so the price is half of the others.
On most models, they include the mounting bracket. Some have lights and some just reflectors. They sell from small to large sizes.
I have a leather covered one that is awesome but it is smaller because I have it on my 150.
Two people in my club have the larger sizes which are comparible to the 46 and 52. They are a nice case and mount and dismount just like the Givi. I can vouch that they are totally waterproof. Have been stuck in a driving rain. I also fit two file boxes with 100 file folders in each on top of each other in the small case. It holds quite a bit.
Their web site is
www.cosmotor.com or it would actually be better to call them at 215-672-9100. There is a picture on the web site under accessories, but they do not show all the boxes. You cannot also order from their website, but I'm sure they could fax you a copy of all their models because they are still setting up their website.
You won't be sorry you called them. They also have a bracket that will fit the majesty.