Not sure the brands off the top of my head, but friend ran a catted and non-catted on his 340i (same DPs as the 540i). Only dyno'd FBO with meth on a jb4 but should make around 20whp usually on just a DP. He said power between the two was the same and no CEL without a spacer on the catted. I'm picking up a VRSF catted myself in a couple weeks.
I know it's not the same but might be helpful. You can listen to his sound clips on YouTube:
https://www.youtube.com/channel/UC9P...c3x5lybH8sFoNw