Thanks folks!
No mate it's not a genuine CS rear, it's the RT-P copy but looks just the same and the fit is spot on.
It was a PITA to fit , trying to slide the back box into two pipes and the rubber hangers simultaneously nearly pushed me over the edge lol.
Yeah will get a vid up as soon as I get chance. It's so quiet compared to the k1 but then anything would be lol.