On later models the CAT was moved right up to exhaust manifold, this reduced the heat up time ( CATS do not work well until they are really hot ). IIRC the Civic has always had the CAT near the manifold, but maybe due to limited space in Jazz engine bay Honda may have fudged it a bit on MK1 Jazz. I believe CAT was repositioned in later models to reduce emissions and not to stop it getting nicked, later CATS also have far less precious metal in them, making them less attractive to steal.