Just going on the looks alone, I'd say that any 16v model one should fit (it was the K1 that first saw the round silencer after the square one on the 8v bikes) but I'm not certain about Cat-equipped bikes (it was an option from some point).
Herr Remus Unt Der Sons MAke a marvellously fruity straight thru exhaust when cou-pled with a K & N and a Chip of the silicon variety can give a rice burner a startle or two