The SLP cats on my Roush are only a few inches of the ground. I don't scrape going down the highway or anything but they do touch over speedbumps and entering my driveway. The car itself doesn't sit that low but it is lower than stock. Any lower and I would have a lot more problems. I have read on fnsweet.com (Roush Site) to raise our SLP cats, which naturally sit very low, you can:
1. Loosen the bolts
2. Place a jack underneath the pipe near the cats
3. Jack the pipe a bit
4. And retighten the bolts
I know mustang owners with BBK midpipes who have had success doing this although it seems there must be a pivot point in order for this to work and I can't verify whether or not there is with the SLP midpipe bc I haven't tried it. Keep in mind that in doing this you run the risk of get an exhaust leak somewhere but I think its worth a try. Hope this helps.