Slightly off topic, but related....
Here's another convertible that appears to have the 'Competition Suspension'.
However, it does not appear to be a K-code, but rather a S-code. The air cleaner is the tell.
As previously mentioned, 21 convertibles were equipped with the 'Comp Susp' option, 19 were S-codes.
No further info on this car in the photo, but...
the photo caption mentioned an August 2011 Mustang Monthly issue having an article.
Anyone have that issue they can scan and post?