Ok I will try this again. I have attached a link to a recording I made of the sound. Please ignore the video quality as I was concerned about capturing the sound. As for the issues I am having;
The car is pretty sluggish especially at lower RPM range. As I hope you can hear, the engine sound seems to be coming from the drivers side of the engine bay. I have no codes, or CEL. I have replaced all CPS, put in VW MAFS, and replaced pre-cat O2 sensors over the past few months. Not much change. I suspect it may be related to the VANOS but not sure.
YouTube - E39 M5 engine sound