Not to beat a horse (or snake) to death, but any chance you may have mistaken the new Shelby Cobras for a 2003 Viper? They make then in all the colors you saw, and I have seen one,and for a few moments, I thought it was a concept Viper too. I think they even have snake type logos which could throw you off.
They have a giant hood scoop, a soft convertible top, funky rear end profile,and large tires and wheels.....