[jmg]

Your M1 to M2 toggling is the biggest tell and the easiest way to diagnose.

Reprogram your M1 to have the M Adaptive to default instead of sport. Recreate the conditions in which toggling to M2 triggers the sound. Did it happen again? If the sound disappears, then it's most likely related to your suspension. Do this a few times to make sure that the results are consistent enough to make the correlation. When you are convinced, go back to stock suspension and see if the problem goes away with M1 suspension is set to Sport+. Problem solved. Contact Dinan about replacing your parts, it's warrantied by Dinan.


If the sound doesn't go away, do the same thing for the transmission, steering, and throttle. Steering might be different for you since you are in non-sport in M1.

If you find that the throttle setting has an effect on the sound, then it might be your exhaust, or more precisely the exhaust flap that opens up the other side of the exhaust. When in efficient mode, the flap opens and closes during certain instances of throttle. It's open full time in sport or sport+ mode. Does the sound appear when in sport modes? If it does, you could rule it out since it doesn't move in those modes. Have your shop look at that exhaust and check to see that the flap is operating properly.

Anyway good luck, and if you do solve the issue please keep us informed!