We are heading into the colder seasons of the the year.
Does your vehicle's Drone noise change with air temperature?

I have been toying with the idea that the RPM and throttle setting where drone occurs could be shifted by injecting air into the exhaust with a 12 volt compressor. Water injection might work also.

Cooler exhaust gas should have a lower speed of sound,
which should shift the conditions where the Drone is loudest.

Someone adventurous might also experiment with adding E85 to the fuel.