Here's an update on my pipes, I cut them on the bandsaw and took around half the length off the body of the pipes. Because they are Tourer pipes they are mounted differently and had to be turned 90 degrees so the mounts were reusable. 2" perforated tube and glass wadding have been used to dampen the noise and then I welded them back together, the rhs did take a bit more persuasion to fit though because the R3T inlet has an offset on the original which is different to the R3R.
They mount onto the R3R brackets, still use the covers and all the welds are covered, sound isn't too bad either. If they stay on the bike they will be getting coated in heat-proof black along with the header covers.
I'm undecided if I like them to be honest and may just make my own stainless end cans but it was worth a day in the garage playing