Splat789
Glad to be able to help. I completely understand your frustration. I had the whistling noise for a long and at one point I even did a "ghetto fix" by disconnecting the tube, capping off the hole from the plenum, and sticking an air breather filter onto the tube. The whistling went away but it caused an intermittent IAT sensor fault which i thought was unrelated and spent months trying to figure out the cause!
I've owned the M3 for ~5 years and have continuously had misc. issues.
I've finally figured out and fixed all except one.... a buzzing sound at 3k RPM...sounds like it's from a heat shield
lol