no it wont fit a leon cupra r, everything is different. i dont think many decats are available to fit the cupra r with standard downpipe the only one that bolts to the standard downpipe is a miltek sports cat or you may find something on ebay. a normal cupra one wont fit or any other 1.8t
i picked up a blueflame downpipe and decat then turned the decat into a sports cat by welding in a 200 cell sports cat. alot cheaper and does the same job!
i went down the decat route and to be honest the car felt slower, it just sounded ALOT more noisey. the day after i put a sports cat in. decat will cause you emisions problems and its only really anygood for a biger turbo car the k04 is only a smal turbo in comparison and needs a cat in place.