I am doing a HT setup for a friend. There are both high voltage and low voltage single and double gang boxes that I need to extend wiring to/from. I have plenty of experience in installing both new and old work boxes, but not much in modifying new work boxes. Would I be better off trying to remove the new work boxes and just replace them with old work boxes? If so what is the easiest way to get them out of there with the least damage to the drywall. Or would I be better off just drilling holes in the existing new work boxes and go from there?