Mad WRX

Hi, I'm stuck with a bit of a problem, I want to change my exhaust system on my 01 bug eye. The problem I'm having is, I've phoned a few places, Larkspeed, ABP and so on, they all obviously offer the full exhaust systems but I don't want a de cat down pipe, I want a sports cat so it'll have a chance of passing mot. They all want to charge me nearly as much for the sports cat down pipe as for the whole exhaust system, do the ones on ebay fit onto most exhaust systems? Or is there a shop out there with reasonable prices for a sports cat down pipe? I know it's not gonna be super cheap, but any bit of saving would be excellent!