[Year's_End]

Originally Posted by CanAutM3

Or maybe the anti-lag trickery at work.

Possibly. I've noticed that this "belching" noise isn't exclusive to the F8X's though, and it's becoming increasingly common amongst a variety of OEMs. Most ZF 8HP-equipped models, be it BMW or Jaguar, exhibit that exhaust rip on upshifts. As do many MBs, Audis, etc. Hell, even a ZL1 equipped with a 6MT and a supercharged LSA will do it, so it might not even be related to a turbo setup which the anti-lag feature would be appropriate.