Hellcat and GT will not be competing with each other. The question to ask is will the Shelby beat the Hellcat. And If I had to guess I would say it will out handle the Hellcat at least, might not quite beat it in a straight line. It will be interesting to see what they do with the Shelby in response for sure though.
My signature consists of a simple fact. Mustang is a muscle car. Have a nice day.