Well this site says 14.3 1/4 and thats with a heavy convertible.Take .2 off for weight and you have a 5 speed coupe that will run 14.1 in the 1/4.
Heres the link:
http://www.bradbarnett.net/mustangs/caroline/specs.htm
Heres another:
http://web.radiant.net/kms/specs.html
Look under ford.It says a 1999 mustang gt coupe ran 14.0 1/4 mile and 5.4 sec 0-60.And a 99 gt convertible with an automatic ran 14.6 1/4 amd a 0-60 at 6.2 sec.
The places where your looking at is giving you stats of mustang gt auto convertibles not 5 speed coupes.
Here is another one:
http://www.modernracer.com/mustanggt.html
If you look at the very bottom it will say
mustang gt competitors,350Z.They both run the 1/4 mile about the same with the mustang gt at 14.2 sec. and the 350Z at 14.1 sec.
This sits says 0-60 in 5.5 sec.
http://www.carseverything.com/conten.../article/39.1/
It says it in the middlle of the page.
This site says 0-60 in 5.4 sec and a 14.0 sec 1/4.
http://www.worldclassmusclecars.com/1999MustangGT.html
This place says a 14.4 sec 1/4 but thats with a convertible.With a coupe which is around 200 lb's lighter it should run a 14.2 sec 1/4.
http://www.theautochannel.com/vehicl...russ0023a.html
This site says 0-60 in 5.5 sec and a 14.0 1/4.
http://home.thezone.net/~mus_tang/2000-2.html
If you read this page it says a mustang gt runs a 14.0 sec 1/4 and a 0-60 in 5.4 sec.
http://www.jhammy49.com/Pages/99stanggt.htm
If you still don't believe me that mustang gt's run low 14's stock I can continue posting more sites for you.Most of the sites say a 99-04 gt runs a 14.0 sec 1/4.
To conclude everything ,there are good drivers and there are bad drivers.
Some people will run better times then others.How would you like it if I said a nissan 350Z ran a 14.9 sec 1/4 even know the driver sucked.That doesn't mean all 350Z's will run a 14.9 sec 1/4 now does it. 99-04 5 speed Mustang gt's are capable of 14.0's and 14.1's but it's all on the driver.The guy can run a 14 flat and another guy next to him can run a 15 flat.