I have this buzz sound. It's not as pronounced or as frequent anymore. But I got it on video. If thats the sound you get, it's the exhaust flap actuator.
I also have this whistling sound like the turbo is spooling up in Gear 2, 3 and a tiny bit on 4.
http://www.youtube.com/watch?feature...&v=BLZ35rC2dDE