Just put on a new 18" Magnaflow muffler (#12288), keeping the existing pipes and leaving the resonators on. It's been on for about 24 hours. So far, the sound is perfect. Compared to the stock muffler, this is a little deeper and meaner but not too loud. On the highway, I can definitely hear it in the cab, but not too distracting. I could immediately tell a little boost in performance/horsepower. MPG- nothing noticeable yet, although I've had a bit of a lead foot.
I've received some great feedback and help from the community over the past 3 months I've been a member. Here is a video as a thank you for everyone's help.
Thanks Ram Forumz