Open exhaust flaps in the city center forbidden?!?!

Hi, was stopped the day before yesterday by the Kripos belonged to the “autoposer” group haha. The thought mei car would be loud and I should drive with closed flaps. They also did not measure at all because it is registered with 107db. The meant avoidable noise is an illegality, and my car could also move quietly if the flaps were closed. So for me this has no legal basis, because where stops avoidable noise where does it stop? I could also take the bike Instead of a car, avoidable environmental pollution would be what is also an illegality. My car has such a license and finished. I am also net heated or so 3-4 t turns in individual mode and fold open. How do you see that? May they force us to drive like a diesel through the city center? I am also not one of those who make 10 rounds in front of the same bar and give full throttle. However, I do not want to hear what I drive, namely a V10 sucker^^ VG Gimix