actually eaglr, car and driver did a test between stock 05 mustang GT and the GTO. the stock stang won. granted, they went back and forth, GTO won here, stang won there but in the end, they picked the stang.
Funny thing is this the 04 GTO beat the 04 Stang...the 05 stang beat the 04 GTO...the 05 GTO beats the 05 stang in every performance test they chose the stang due to its styling and thats all...have the article in front of me.
I own an 04 GTO, test drove new stang also comparing it to a stang is apples and oranges, the GTO has a much much more refined interior than the stang and I like the suspension more on the GTO. The GTO came with every option I can think of aside from navigation (I am a man i dont need directions). I liked both cars alot, but i went with the GTO I am one of the few people who actually like the body style, the engines rumble is awesome.
Hell i dont even like the 05 GTO with the added scoops and seperated exhaust.