Hmm...i dont know how much lower my car is from stock, but i scrape everwhere i go. If i am on a highway and hit a decent sized bump in the road i usually scrape. If it is at night you can see the sparks behind me. It doesnt bother me, you just learn what bumps to avoid. I really have to watch out for Speed bumps though.
I have the BBK LTs and the Saleen suspension, scraping or not it is worth it.
Like i said, i dont know how much lower my car is from a stock GT. My car has the Saleen suspension on it, so if you can find out how much lower thier set-up is from a stock GT that will answer your question. Sorry i cant help.
my car isn't lowered... but i have hit the LT's and the rest of the exhaust a couple of times already. i even have a small dent on the right side header.... but it was my fault. i went too fast on a speed bump.
If anyone does know the difference in ride height b/w stock gt and saleen please post. I am looking at getting the bbk LT's and would like to know if I am going to have problems with scraping.