A FoST driver in SoCal found this. Instead of completely replacing the antenna, it covers the base (where the Sirius Antenna is) and just screws into the hole for the aerial. Unfortunately it's listed for FoST colors only, which means there's no color match for Green Envy or Molten Orange; but they do offer gloss or matte black.
http://www.focusstshop.com/Visual-Garage-2013-14-Ford-Focus-ST-Shark-Fin-p/vg-sfa13.htm
Colors available:
http://www.focusstshop.com/Visual-Garage-2013-14-Ford-Focus-ST-Shark-Fin-p/vg-sfa13.htm
Colors available:
- Gloss Black
- Ingot Silver
- Matte Black
- Oxford White
- Performance Blue
- Race Red
- Sonic Blue
- Tangerine Scream Tri-Coat
- Tuxedo Black