gnx's are crazy.. i still have yet to see a modded run. some guy has one that works at a local oil shop, but I have never seen him driving it.
like many have added, the original poster was referring to the 3.8 s/c V6 regal. Its pretty much identical to the GTP in almost every way. same engine, chassis etc... i think the regal is a little bit heavier, but much like the gtp, with a pulley, intake, exhaust, you can pull off mid to low 14's.
some are saying that they run mid 14's stock, but that is very rare. many people also think the gtp runs mid 14's stock, but truth is that the LARGE majority will make very low 15's and high 14's. the same goes for the regal.. although i have noticed that more people tend to be a bit faster with the regal, (14.7-14.9)