I don't think its from the different diameter mid pipes or the H pipe. I can't believe that your having noise issue with Dynomax turbo mufflers and resonators. I know alot of people that have them with out resonators and they are pretty quiet. Are you sure they are turbo mufflers and not one of thier other lines?
It has an unpleasant drone at 30 mph (3d) and 50 mph (Od). Sound like pulling up the 120hz lever on your HiFi equalizer.... (boooooooooooh)