I live in a town that has lots of tree lined streets, lots of underpasses and quite a few other obstacles to Sirius reception. I had the issue of "intermittent reception" on my Tri and still on the Ultra. So I did the same mod.
Step one, remove outer faring and Windshield, then locate the antenna. It was a little different on the 14 Ultra than on the 15 Tri.
Step Two, gently pry the antenna off the plate (it's just double sticky tape). Then figure out on the dash where you want to mount it (I chose just right of the vent) and ensure there is enough cable to put it there. Then you need to "notch" the dash, so you don't crimp the wire when you put the windshield back on. I used a small jewelers round file, tedious, but, makes a clean notch and you don't run the risk of making it too big. Too big, water can leak in, too small, you could crimp the wire.
Step 3, I used a 3m exterior grade double sticky tape to remount it. I used a hair dryer to get the old tape off and alcohol to clean both surfaces.
Step 4, Put the outer fairing and windshield back on. Do Not Over Tighten the screws. Theses threaded mounts in the inner faring are brass seated in plastic, you can easily pull the brass out on the plastic.) If you do, gently tap it back in after putting a couple drops of super glue around it). Here's what it looks like on the dash, inside and out.
Just as a update on performance. I went for a ride down a street that had lots of trees, no loss of reception.