From what ive been reading they would be about even.
If you want a car thats fast & cheaper Buy the mach 1 or the cobra.
If you want a car thats fast, refined, handles great, has cheaper insurance
and has a beautiful interior then buy the GTO.
I think the GTO should be compared to the BMW 3 Series not the ford.
I had a mustang a few years back & there is no comparison
the GTO is a much better automobile