My C5 Z's were all pretty heavy modded so I can't really compare to those. My last one was a C6 Z and you can definitely tell a difference down low. However under the curve is where the LS7 makes it's money. I haven't had the chance to ring out the GT to 8k yet, so I don't have a comment on...
Had the itch for a new ride and my last 3 fun cars were all Z06's so I decided to get back to my roots and get a Mustang. All of 30 miles on it so far, but love everything about it. Future plans are some catch cans to hopefully cut down on oil consumption and some PPF to help with the paint...