Hey everyone. I have an 06 cts 3.6L and I am starting to get exhaust in the cabin while driving. It just started do this. The cell is not on and it seems to be running perfect even though it is 20 below right now. Also when this happens I have my heater blowing full force. It is to cold to see if it happens when it is off. Any suggestions? I am thinking it has something to do with the heat shield. Oh and the exhaust it stock and is in good shape.