I dumped my 2013 SHO because of this clicking problem, as well as some other issues. Three dealerships had the car five different times by the 20k mile mark and the clicking remained after they replaced the steering rack, hubs, and pretty much everything else they could think of.
I liked my SHO a lot when it was working properly but it just had way too many issues, way too early, for me to keep it. Dealerships did what they could to make it right but Ford itself was less than helpful.