Originally Posted by Hotrod99
Well either that, or i'm clearly not hearing what others have heard.
I've heard the words "Boom" and "Bang" used in some posts. Mine is neither a boom or a bang.
Drone isn't exactly a Boom or Bang, but rather a deep low frequency sound that reverberates throughout the cabin. It should be noticeably louder than the normal exhaust note and it usually occurs in a certain rpm range. I highly doubt it is an engineered feature, but rather an engineering miss.
I don't have my 1M yet, but I currently have a performance exhaust on my 550i that drones from 1,500 to 1,900 rpm. It can be annoying depending on my mood.