If he doesn't want to hack it up he should remove the entire exhaust from the headers back, get an OR pipe and if he wants a dronemaster system he should just get the cat back. This sort of swap is easy enough to do in a driveway.
Just be aware that if he is having a shop do the work, no legitimate shop is going to delete his cats for him as it is a federal offense to remove them. He would have to put on the OR pipe himself and if that is the case, might as well do the whole exhaust himself.
Hand tools, WD-40, good set of ramps/jackstands and a good 4 letter vocabulary is all that is required.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.