Ford built and designed all
Ford built and designed all the GT500's from 2005-2014. The Shelby name was licensed from Shelby American for these models but they had no direct input into the design. The 2014 is still the most powerful production V8 currently available and will be until the Hellcat is released. This title will likely be short-lived as plans are already underway to build a GT500 using the new Mustang S550 chassis which which will have more horsepower than the Hellcat. How much more is not clear, but it will be more and in a much lighter chassis allowing it to easily outperform the Hellcat.