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.
-Mike