Annoying whistle at 2K RPM

[garfield81]

This is in regards to a 2006 3.0i X5 with approx 70K miles. I have been noticing an annoying whistle at about 2K RPM. I have tried to reproduce the whistle while parked and cannot seem to reproduce it so its only while moving. Last year when I started hearing the noise I checked the forums here and most suggested the intake boot which was also the case for me. So I had that replaced but it did not completely get rid of the whistle but I gave up on it. It is now bothering me back again so I checked the intake boot and its still new with no tears/holes (even on the underside).
Couple of other suggestions I found on the forums were to check the vaccuum hoses but I don't know where to look for them. Also read that a vaccuum leak would lead to a higher fuel trim. So I plugged in a scanner with live data and the STFT would jump no more than 3% (this is only while parked. Did not test while driving)
Any suggestions would be appreciated and thank you.