The burbles are entirely fake made by DME programming.
On any regular car there is no fuel available on overrun to cause burbles. It's meant to sound like old carburettor engined cars that burbled on overrun naturally.
Back to my N54 335i, tuned, DPs, exhaust - never a crackle or pop in 4 years!
That said i'm going to disable burbles on sport mode only but keep them on sport+, with BM3 you can wind up the "aggressiveness" level too.
So i'll go OTT in sport+ which I don't use much anyway (just for special occasions)
