707 Hell Cat, what does it mean?

Ran across this one on the Hellcat. This is one that was at the hometown track. Great Lakes Dragaway. Not misspelled, the way they do it. Looked for the date in article, didn't see it. I wished I was there.... Darn it.

http://blogs.cars.com/kickingtires/...-the-challenger-srt-hellcat-to-the-strip.html