Quote:
Originally Posted by Hapbob
I have stock set up on 2023 M240i. I live cold climate and vapor only comes out of one side on start up. Can someone educate me how this exhaust works ? Is it duel or not ? The picture in this thread looks like it should be both in use?
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There is a valve that keeps the left exhaust closed until a certain rpm and vacuum is reached. At that point, it opens the other side. Pretty clever bit of engineering to make sure the engine and exhaust are working together for optimal performance (which for BMW DOES include efficiency and emissions as part of that target).