So I was finally able to figure out what the noise is... It is the Idler pulley just above the alternator. Bearings were shot, replaced with a new OEM one and its quiet once again. The cricket sound some of you are referring to is probably the whistle of the intake manifold. And almost all 3.0 BMW's seem to do it. My neighbor has a 2004 330i and it makes the exact same sound as my 03 X5