My 550i got the CEL on AR catless downpipes.
Sound is amazing. I could say no increase in exhaust sound, but the whining of the turbos are more audible now. I actually been asked once if I had a supercharger on the car.
Love the whining sound.
F10 550i M-sport: Space Grey/Oyster Black
E39 M5 : Carbon Black/Caramel
E39 520i : Titanium Silver/Beige (Sold)