Butler makes and supplies the exhaust system to RMS and possibly to other workshops too (thats from the horses mouth). If you absolutely must have the "RMS" exhaust you might as well go to Butler directly. He's just down the street from RMS.

Butler Built Performance
Unit 3/16 Cohn Street, Carlisle.
Tel: 9472 7373
(Norm Butler)

Had my exhaust done by Butler. Paid $1500 installed. Much too droney for me. I changed the rear muffler within 24 hrs to a more restrictive one to cut the interior drone. Still wasnt happy. Finally had a Jap muffler fitted and its much better.

If i had to do it again, i'd buy an imported Japanese brand exhaust (Fujitsubo, HKS, Apexi...), way better quality (mandrel bends and not cut and weld job)and sound (get JASMA approved systems which have to meet strict decible ratings). Unless of course you want LOUD.....