On a MT H2H the '11 Mustang GT 5.0 was compared with a BMW M3 (V8), and the Mustang performed similar to the bimmer on all aspects. Also during that year the Mustang GT was compared to the 5th gen Camaro, and the Mustang was way better than the heavier '10 Camaro SS.
MT later on compared the '16 Camaro SS with a BMW M4, and the Camaro performed also similar to that year's Bimmer. And performed way better than the newer model '15 Mustang GT, that now had a new IRS instead of the live axle of the previous model, but now was heavier.
On my personal experience:
-The '11 Mustang GT 5.0 MT performed great at the track, it was very nimble and had great stability (I had my suspension modified for the track), I even tracked it against a BMW M3 DCT V8 which had aftermarket bigger brakes, still my 5.0 was able to keep up with that car.
(My 5th gen Camaro ZL1 felt way heavier than my Mustang, but it handled great and felt very powerful with that strong SC V8).
-My '16 Camaro SS also a very capable great handling sport car,
but I didn't had a chance to track it.
Probably at the track the newer tech 6th gen Camaro SS would beat the '11-'14 Mustang GT 5.0.
Both cars are great performing sport cars each one during their own production year.
The only performance difference that I noticed from my previous C7 Corvette Stingray Z51 compared with my newer 6th gen Camaro SS, is that the Camaro feels heavier on the rear, less nimble than the C7 Z51 while changing lanes fast.