I just called the exhaust shop that had great reviews on Yelp. It was a one-man shop, but basically he told me that my car is going to drone and there isn't much he can do about it. He said I'd need a muffler that has both packing material and chambers to break up the exhaust while quieting it. He said he's worked on a couple of Dodge Darts and there's no room in front of the mufflers for him to put anything, as I suspected with my 2" between the centerline of the tube and the floor pan. I asked him if there was anything we could do on the tailpipe end like adding a glasspack, chambered muffler, or resonator and he said that odds are all it will do is quiet the car down.

I asked him about the turndowns too and his response was, "Resonance is resonance." So, I'm not sure if I should get another opinion or take all of the knowedge I've gathered from this thread and try something.

I think my next step may be to grab all of my blankets, like mentioned before, shoving them in the trunk, and seeing if maybe that will help as he hasn't had any experience with sound deadening.