An easy and very cheap way to do it is to replace the resonator with a straight tube. The factory muffler has a particularly raspy note at large throttle openings, and the absence of a resonator would certainly accentuate that.
What I did was leave the resonator in place and an swap the factory muffler with a Magnaflow muffler PN 12388. Like you, I don't see anything in particular wrong with the factory exhaust tubing, so the 12388 is a good choice. Its length, inlet diameter and outlet diameters match the factory muffler, so it's a straight weld-in swap. Cost is only about $120.
I had a local muffler shop do the work because I thought that the SS factory tubing and the SS Magnaflow would preclude me doing my own work with my gas rig at home. I got a really bad installation, and in rectifying it found that I could have done the work myself. The result in terms of sound is a slightly louder exhaust note, smoother, and a bit lower in pitch. The WOT raspy characteristic of the factory can is gone, and I kinda miss that. As the Magnaflow can is a straight-through design, I think the truck probably performs a bit better at large throttle openings, but for normal everyday driving (my Raptor is my daily driver) there's no difference. No difference in MPG, either.
