I know some people here might not be fans of Ponies or muscle growth but, there's a pretty well done sequence by Clock-Face on Fur-affinity where a bad batch of Cupcakes makes people into Buff Anthro Pinkiepie clones.
http://www.furaffinity.net/user/clock-face/
Personally pretty kinky to me, although I understand it's not everyones cup of tea.