#1 Post YEA!
Unit does have some points, comparing the 4.6 to the 5.0 is a very wide range of mustangs, a 93 AOD GT Vert will not run what some of the lighter, cheaper coupes will.
Likewise, that new Bullitt wont run what a 99 Auto Vert will.
these ranges are so large that, when the cars condition's (mileage, etc) are factored in that it is a push, with mabye a little going to the new GT.
Congrats in 10 years the mustang got a little faster STOCK VS STOCK.
Start throwing parts on and you will not see the same gains that the 5.0s will, and start adding non motor parts to the 5.0, (eg: gears, slicks,the like) and the 5.0 will run very close, if not, the 12s,not the 13s.
If you want a fox to compare look no further than Bob Cosby's 88 SD Coupe. All $12,500 it cost NEW. He kept impeckable records from when he started racing the car, when it was new. Take a look.
http://members.cox.net/bobcosby/stang/