ANGLE is your Friend!
I'm currently on TEIN's (installing Stance Coilover's in spring)
I'd say I'm dropped 1.1-1.2" as the TEIN's settle quite a bit....I have the CF cans and have not scraped them and roads here are horrible. Getting out of my condo parking, I seem to scrape the brace that covers the y pipe before anything else. And thats everytime, I cringe, but at least its not my exhaust.
You just gotta be careful (smart) especially on roads you aren't familiar with.
I think if you are on H&R which slams you, you run more a risk of scrapping for sure (they are almost 1.5" drop)