Ok, second update on this. Had the Rebel out on the highway, and since I disconnected the ANC microphones I am definitely noticing a change for the positive. Exhaust is still deep, but I don’t have that boomy drone any longer. I am at a loss as to how much noise the ANC must have been pumping in to create this. I can hear my stereo clearer, too (not that my hearing is anything great to begin with - I am a firearms instructor and play guitar - so I love the Glock comments
).
To the posters who suggested disconnecting the ANC, if you ever pass through western New York, I owe you a beer or a whiskey.