Quote:
Originally Posted by ND40oz
My X5's exhaust did the same thing, I always figured it was just something really quickly loosening back up as the metal expanded do to the quick warm up.
It definitely wasn't the flapper valve though, since I had the M Performance exhaust which doesn't have one.
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On the X3, if you stand outside it when it is cold and have someone start it, you can watch the change in the exhaust when the valve closes. It's the flapper valve.