Are you ready for the price though ............ https://www.bmw-motorrad-bohling.com/bmw-akrapovic-exhaust-pipe-k1600gt-k48-k1600gtl-k48-euro4.html
The reason why I bought the 1600 when it first came out and still have one today, was precisely because it didn’t need anything doing to it to heighten my ownership ‘experience’.