decatting

Been thinking of this for about 6 months after watching a mate mess around with a Matiz he had at his garage in for repair work..... Now I know if I decat the the exhaust, I'll get the EML on (until I map it out), however, after seeing what my mate did for a laugh on a Matiz, I was thinking...

would like to de-cat my lcR, already have a milltek cat back but they only do a sports cat, no de cat pipe, will any other decat pipe's fit or do i have to stay with milltek and pay 600quid for a sports cat!