Hey guys first time poster, just recently got a 535i and had this issue come up. Honestly I'm thinking it has to do with the turbos because I did have a slight hick up (one time occurrence) and tonight I notice the car was noticeably slower when trying to push it.

I also noticed this sound soon after I had pulled out of a turn and nearly redlined. If any of you guys have any idea what may be causing this, then it would make me a little more at ease.

Thank you