Yea, running over existing sheetrock is a pain in the ass. We did a guy’s home theater a few months back and had to cut up the ceiling, twice. To make matters worse, it’s a stamped ceiling! I hate that crap. We installed a projector in the middle of the ceiling and motorized screen along with the surround speakers. Pulled two hdmi cables from the closet where everything lives to the projector, one was for the dvd/cable box, the other was for the xbox. After we got the rock back up and mudded, he decided the xbox controllers didn’t reach, so we pulled the cable over to the bar about 10 feet away, no problem we thought, except we forgot the hdmi cable is directional when they’re that long. No way we could pull the cable around the bends, so we had to pull the rock back down and refish the cable around the other way. Luckily the dude wasn’t worried about the ceiling, he had a guy that could retexture it.