One problem related to manifold/header/muffler/tail pipe has been reported for the 2007 BMW 328. The most recently reported issues are listed below.
I have had numerous problems with over heating. Every time I have taken it to the dealer for this problem they have found multiple leaks and the manifold cracked (not diagnosed in one visit these were found after multiple visits). It still does it and now they claim they cannot find anything. They want proof that this is actually happening so I am going to film it when it happens to me again. The incident that happened on 12/31/13, I was driving on a road to get to a resort, this road was not elevated in anyway it was level. It happens every month or so.