Hello Mavros,

There is no performance change on either pipe, as a matter of fact, Tuny my teammate, had his 821 cut and welded to fit his Xurama and has performed identically than mine.
He cut about 1.5" I think, and that is another option you can explore, so you can have your custom pipe, and it is not louder, we measured both and are pretty much the same.
Tuny has pictures of the pipe on his built thread.

Hope this helps.