ArcherL, I bought mine from Straight Line Racing. It's a Remus and intended for a GSX-R 600 but fits the standard 1150 CAT perfectly. Makes a nice noise and looks very tidy. It cost £54.00 delivered. You only need the end can, give them a call as they are very helpful and have sold loads of them to fellow Tossers.....
Alternatively, for £30 less buy one for Bryn of this parish (see Vendors of Innovation for link). Just take the standard heavy silencer off and replace . I run mine with a K&N filter, no problems after about 3000miles