I spoke to Mercedes regarding the quad exhaust conversion and they said it is not possible on the 4 cylinder set up. So this would mean 180 and 250. Obviously we know it can be done because a few have done it via CKS but this is the reason the exhaust is not genuine AMG. Merc are basically saying we can't do it by using genuine merc parts, therefor won't do it. Which I suppose is fair enough.
Merc also said it would affect warranty as we all already knew but it should affect the entire warranty. So if whoever supplies/fits the quad conversion supplies a warranty you should be covered, "should" lol
They told me to keep all original parts as the new exhaust despite how amazing it looks WILL affect the cars value. Suppose this only applies if your gonna hand/sell the car back to merc after ur deal.
I'm still up in the air about having this done, just can't decide.
Hope this helps