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.
The most recent night when I brought it home, it was about 50-60 degrees outside which is usually about 30 degrees cooler than when I normally drive it. I did not notice a change in drone tone or location. The drone almost always occurs between 1800-2100 RPM while I'm inputting some sort of throttle.
