I have a domed emblem overlay of the Berg Snake on my SGT steering wheel center and faux gas cap. It looks great, and you don't have to remove the existing emblem.
Check out Devries signs; They have lots of Mustang overlays for horn buttons, gas caps, and wheel center caps.
(As a new member they won't let me give a link on this site yet.)
2007 Shelby GT #2737, White 5-Speed.