Twin-pipe rear exhaust

[TheTinkerer]

Hi all, my 328i has a twin-pipe rear exhaust. After clocking a few thousand kilometres, I notice that one of the pipe has a lot more black (dirt - exhaust waste) than another. Is that normal? This is my first car with a twin-pipe exhaust. What about others with the same model?

 

[Devillian]

That's actually pretty normal. Because the stock exhausts are valved. So most times, only one of the tips is actually flowing the gases out.

See the OEM Diagram and you'll have a clearer picture.
View attachment 27449