If you are standing behind it, and it rev's with the valve open, it hurts the ears. With the valve closed, it's still pretty loud. I have the Sport exhaust and with the valve closed, it's quieter than stock in some instances, but with the valve open, it's about 80% of the volume of the F1. I thought the Sport was loud, the F1 is just insanely loud.
2008 E90 AW
Exhaust: Innotech full system with magnaflow cats.