well it might be the same for pre-98 contours as the difference between mk1 and mk2 mondeos. on the mk1 mondeo zetec the cat is down under/behind the engine, on the mk2 its just under the header on the front of the engine. however, zxtuner headers/decat pipe fits both mk1 & mk2 mondeo's.
regarding the cat, to make the header work better either have no cat, or use a high-flow cat (having no cat will give you problems with emissions laws but you may know a way round it
). using standard cat with the performance header will still give you a nicer sound but probably no performance gain. you could put a resonator in instead of a cat for more back-pressure.
