i personally have never seen a s197 run better then 13.7 stock, there are some freaks out there, but thats rare, a s197 in the mid 13s is like a ls1 in the 12s

 

most of the GTs i've seen at the track would be lucky to dip into the 13's...

 

there was a guy back when i started modding my s197 (late 04/early 05) that ran a 13.23 @ 102.xx bone stock with a 1.86 60' on stock pirellis. he posted a vid of a high 13.30s run. what i am getting at is that the car running LOW 13s is like a ls1 running HIGH 12s stock...its only a 40rwhp difference stock, and the gt has better gearing, so that is quite reasonable.

realistically, MOST s197 guys will run 13.90s-14.20s stock, because they either don't know what they are doing, or just haven't raced much before. It is the same with ls1's...most people that i have ever seen run them do 13.40s-13.80s stock, and 12.80s-13.30s with bolt-ons...of course they are capable of a little more than that, but honestly that is what joe schmoe runs in it. People who know how to handle the new stangs will generally run 13.70s and best down into the 13.50s or 13.60s stock, just like i am told that people who can handle ls1's quite well will run 13.30s all day, and best down close to 13.0 stock.

i never ran mine stock, and i wish i had nowadays...but it was winter and i had the mod bug already. i ran 13.46 my first time down the track ever, with my only mods being 4.10 gears and a predator tuner to correct the speedo for the new gears (no predator performance tune because i was told not to without an intake at the time). That day i bested a 13.26@106.7. This goes to show two things: a)i could drive it decently, but with 60's in the 2.05-2.25 range, it could have done better, and b)the car is capable of mid 13s stock, unless those gears alone were good for .5-.8seconds in the 1/4

back to topic...
a new edge is a mustang (non-mach or cobra) between the years 1999 and 2004, but more often referring to the 2002-2004 model. the GT/CS is just looks, though it might have a different axle-back, but those won't fetch more horses than i can count on one hand anyways. It should be able to run mid-13s, but he will likely run high13s or bottom 14s when he takes it out. it will NOT run 12s, unless its a car of the custom model "GT/SC"[8D]