Hehe, silly ricers... Anyways..once, long long ago (in the 60's) A chicken farmer was hired by ford..well, he was a bit famous by then as a racer. They asked him to make their luxery mustangs into monster machines. His name was Carroll Shelby, praise thy name. He set forth to make the GT350 and GT500 mustangs for ford. But during this time he worked on another car. The body of a British sprinter, made by AC, combined with the power of the Ford Engine, at the time it was the 289, but later he added the 427 into the light body. This configeration became known as..3 names, the AC Cobra, the SHELBY COBRA, and the Ford Cobra. Now, after shelby wasn't needed anymore they turned our beloved mustangs into pansy chick cars(no offense to the ladies!!) for a couple of years. BUt kept the higher end, more performance models with the name Cobra II..these were equivilent to sh*t covered in gold foil....
And the name has stuck every since, and remains a name of performance and muscle..and something to scare the hair of those nasty chevy drivers!!!..Well some of that may have been of my opinion, most not, but that is absically it. Others may have a better explanation.