LOL, I know when my 99 GTP was stock, I ran around 14.8 stock (never had been to the track before that with any other car). My 97GTP went 14.3 stock (that was my friend driving it before I bought it from him.. it isnt stock any more).
You are right, stock gtps, run out of legs fast. 1/8 mile is normally very strong on a stock gtp but falls flat up top.
I am not sure why, but when mine was stock, I always looked for a SHO or TL/CL s-type or 94-96 impala or what ever... something about haveing to show up the other sedan/family car types. Its silly really but when I first got it, I thought it was some kinda muscle car or something.
Now I don't waste my time on most cars unless the driver is really irritating me or when ever I get a chance on a vette or M3(I love taking down vettes with a 4 door).