I can not completely comment on the drone, as I have not towed with the truck as of yet with this new exhaust.
I do run the Range DFM delete module, you could have tried that before removing the exhaust.
As far as the drone, different engine loads, different roads and speed have any drone in different rpms and gears. does it have some, yes, but I`m quickly past that point. I would suspect it would be worse when low speed cruising, however I have not experienced it yet even with varying speeds, hills, curves, ramps, etc... Ill know more when I hook up the trailer in a few months.