I have the Double Take Enduro mirrors. Less is more. I have the 3 inch arms. On a TW mirrors often double as a tachometer as I shift when the mirrors vibrate. I have a drawer full of Uncle Mao's folding mirrors as back ups or give aways.
If you use mirror extenders (get counter threaded for your right side) and use smaller arms, the mirrors work well (Enduro). They tuck in really nice, but I take them off completely. I have a drawer of Ram mount stuff, so I only had to get the mirrors ($25.00 a piece). They are made in the USA. If you break one they will send you a new one. Again, they come off so easy, why keep them on when you are smashing and crashing. Anything with Ram mounts can be fabricated 100 different ways to suit you.
Double Take Enduro mirrors on 3 inch arms with mirror extensions are the best in the world. Nobody should buy any other mirrors, arms, or extensions. Everyone with a TW should get Double Take Enduro mirrors on 3 inch arms with mirror extensions.
You are getting vibration from the longer arm and the threaded ball. The only threaded balls that work well are the "hex" 1/4-20 or 6M hex. The ones they market (10M) do not work as well as the base with the 9mm hole.
You would be better off getting a 10M x 1.25 pitch x 25 mm stainless socket cap bolt (Yes I am bragging that this little bike taught me the metric system). Put it through this: Ram Mount Motorcycle Base with 9mm Hole and 1-Inch Ball (just use Amazon or eBay)
Put the 3 inch arm over that ball and I think you will be much happier. The way they market it works, just not as good as the right way to install it. No vibration unless I am leaving the ramp to jump the school bus while smoking a cigarette while flashing a peace sign while a scantily clad woman on the back is holding the radio playing I'm the Man by the Killers.