I have an 08 lmm and over the weekend the engine started to make a whistle/whine sound separate of the turbo whistle. It starts almost exactly at 2000rpm and continues after 2000rpm. When I let off the throttle it stops. I tried listening for it in park and it does not make the sound. Also if I manually down shift to get into the 2000rpm range it does not make a sound either. I checked the turbo shaft play on the compressor side and it has a very small amount of up and down movement but I don’t think it’s enough to be making contact. It also doesn’t matter if the engine is hot or cold.