I have to retract my statement.
Someone at Facebook told me that every 959/1299 slipon will fit. He was 200% sure!
So I‘ve bought a 1299 slipon and what a wonder … it doesn’t fit! It’s missing about 40mm at the Y-connector. So …
A 959/1299 slipon will not fit our V2.
You have to install the headers too e.g. a full system. The only exception is the Akrapovic slipon. Here you have to buy the V2 Y-pipe separately.
After I sold my 1299 slipon I bought a new Akrapovic system for damn little money at my dealer so I‘m happy now