6.0L Excursion down pipe?

[Perf Diesel Shop Owner]

Hey guys, I installed a Banks turbo back exhaust last night on a 2004 Excursion and found a wrap around the downpipe I have never seen before. The wrap started at the turbo flange and extended all the way down to the crossmember area. It also had a resonator in it! I have never seen this on any of the pickups I have worked on before? Is this common? I can say 1 thing, it made removing the downpipe a major PITA! The wrap was a heavy gauge stainless steel makeup, with bands every 6-8 inches that were nearly impossible to cut w/dykes! The metal blanket had a Ford logo on it. Im guessing this was OEM. Whats the deal with this and any reason why all the trucks do not have it? Just curious.