It looks like the origin of this set of spy photos is coming from the Mustang6G website forum and the vehicle is a partially camouflaged prototype of what is either going to be the new GT350 or GT500. The current generation of GT500s are sporting the quad exhaust ports, just like the car in the photo, but Mustang6G is reporting that the GT350 will make its debut in April at the New York International Auto Show, which begins April 18, and so these shots may be that very Mustang.   Looks like the photos also show the prototype running on 295/35R19s.  How cool is this year going to be for our favorite car ever?!