Stock exhaust with AR DPs is what I run. DP brand doesn't matter unless their are cheap tinny ones that will allow you to hear waste-gate rattle easily and they dont allow for proper mating with the manifold.. Decided on the stock exhaust for both the F10 M5 and the F85 to keep the cars somewhat civilized. If you're installing yourselfm, the F85 has brackets that are very difficult to access without a lift and special tools
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1. The F10 was cake.
With catless and stock exhaust its loud, and sounds amazing. I'm tempted to grab a Dinan exhaust but I'm just so happy with the stock i'll hold off.