Originally Posted by M3PO
UPDATE! Changing the VANOS units seems to have solved the issue. I let it sit for about 4 days (the longest I've ever let it sit) and I didn't hear it at all!
Yay, always nice to see a resolution that has a pinpointed cause.
The E46 m3 and e39 M5 are notorious for vanos noise especially in higher mileage - haven't heard of too many e9x M vanos issues, but it could be a matter of age/mileage.
We might hear a lot about this 5 years down the road...