I agree with your definition of drone. That's exactly what it is. So if you hear your muffs in the 70 mph arena as I do, you no doubt hear them in city driving at that same rpm. Maybe what I'm hearing is not drone? I've considered that possibility.
Yeah, I think you're just hearing the normal exhaust sound, not drone which will actually sound more like it's coming from somewhere within the cabin.
2013 GT Premium Brembo
MGW, Blow Fish, AM Hood Struts
Tinted, Borla Touring AB, ProCal Tune
Full Shelby/Kicker Audio Upgrade