I have searched a bunch of other posts but cannot seem to find one describing the strange noise from my 04 X3 3.0i. The noise started with a high pitched "whistling" or chirping, coming on about 2500-3500 rpm, under acceleration, then fades out after 4000 rpm or so. Noise appears to be coming from the front end/engine area, really hard to tell. Took it to the dealer, they replaced a rubber intake boot (for $400!!) but recommended a complete brake job, said the noise was coming from the front brakes. I did a complete brake job over the weekend, new rotors and pads (Centric Rotors, Stop Tech Street Pads), damn noise still there!! I have applied the brakes when the noise is loudest, no change, which to me says it is not the brakes. Noise also stops when coasting or when shifting into neutral. I was hoping to have some ideas before going back to the dealer. Is there any items underneath that need to be greased?