Hi Guys, I have a 2005 E90 330i with 69,000 miles. Over the last few months the exhaust has developed a burbling/blowing a raspberry noise at around 1500 rpm. It fades away after 2000 rpm. It is only evident under load i.e. I cannot reproduce it when the car is stationary. I cannot believe it is anything serious but it is annoying and detracts from what otherwise is a superb car. Does anyone have any ideas ? Thanks in advance.