Hi there guys I have a slight issue with my 520d. Now I know the chain rattle sound and the service bulletin regarding exhaust mount. But I have a vibration at idle it doesn't vibrate at other time. 800rpm only soon as I put foot on throttle it goes I've had car in air and exhaust system is solid all the way through. Recently had new turbo but that is fine.I'm concerned as its not air box as I've already secured that.engine cover is off because that makes it worse .and it resonates through back box ....any thoughts thanks in advance.