every car is different, but you can take the basic information from both and get a general idea.
first off i have a 01 mustang v6 manual stock i ran a 15.5@91mph with a 2.3 60ft. stock dyno( 163rwhp @ 5500rpms 200rwtq @ 2800rpms)
with CAI, exhaust, gears (3.73), and a traction lock I run 14.9 to a 15.0@92mph~ with a 2.2 60ft~
with my aluminum drive shaft and UD pulley i ran a 14.64 best to a 14.76@93mph on average with a good run of course with a 2.2 60ft.~ i had a bit more practice and good luck but on average now i run 14.7 and with some good 60fts should be in the 14.55s. the track here just sucks and i cant pull better than a 2.2, and i if i do i alwasy seem to mess up shifing lol. I had a set of lift bars and pulled a 2.0 flat off the line but my used rear end broke and i had to coast lol, i got a brand new parts so it wont happend again, but i took off the bars just in case, so i am once again stuck in the 2.2s
thats about all the simple bolt ons that i can do that are worth a crap sure i could buy this and that and probalby get another tenth or a tad over off but its to costly really. with a chip, and headers, and Hpipe, with an ignition and wires i MIGHT pick up two more tenths....but the real helped is a procharger, stock mustngs with one put down 310rwhp and tq, not to bad over the stock numbers.
take a stock pre 99 gt auto they run mid 15s stock maybe a tad quicker (98s are at tad quicker) stock for stock the gt has the v6 on the street cuz the key to running the v6 is hooking up and you just cant do that stock or on the street very well at all, especially with puny 205 tires lol.
thats just the information i hve seen wiht my times at the track and all my friends mustangs, i can count 30 of them around my area, a little bit of everything. a 96 up manual stock runs a 15.1 ro a 14.9 on average also.