I have the burbles on the M3 CS and of course the IPE exhaust makes a lot of noise which drowns out a lot. What is indicated here before, it is actually an incredibly expensive cosmetic mod instead of a performance mod.
To catless downpipes goes too far for me, with the IPE exhaust it is much too loud haha!
Here a video of a trackday from last week at the circuit in Zandvoort:
https://www.youtube.com/watch?v=7SbRJIx8MN4&t=9s