I hate to be the downer, but there are a couple of issues you should consider before ripping part of the factory exhaust off of a $60K truck because you don't like how it looks. Maybe you already have.
The tubing used by Ford is real good stuff. Hey, it's a $60K truck!. The stuff you by at AutoBarn and that Wagner uses is high-carbon junk. It rots out fast, I've had it turn to trash in 18 months, while the Ford stuff is still solid after 18 years.
Ford installs the huge resonator to mute the Eco-boost motor that otherwise sounds like a little girl's sewing machine. They know folks putting down real dough like how a V-8 sounds or don't like how a little six sounds. Want your Expedition to make like a souped-up Honda? Go for it.
Just tread with caution and consider these thoughts if you haven't already. And good luck with it. Let me know how it sounds and how it works.