Hold up! When I had just 3.73 gears and a Flowmaster Cat back my car ran 14.0's all day long. (car had only 4,500 mile on it). This was back in the fall of 1992! (and no it wasn't 40 degrees either)
True my car as well as the other 87-93 Mustangs didn't make as much power as the new ones, but we didn't weigh as much as the newer Mustangs either!
I have a 92 notchback. My buddy had a Gt with simlar mods and went on average 2-3 tenthes slower.
By the way the car sat on stock Michlins 225/55/ZR16's.
14.05 @98 was the norm with a 2.0-2.1 60ft.
And yes the car went slower with new mods until I found slicks!
Then I broke into the 13's and I was hooked on speed from there out!
My 2 cents and true!