Generally cats that are worth there salt come with a "gram weight" scale of how much prescious metals are used in there construction. From a technical point of view, just saying that a cat has 200 cells is f**king usless, you might as well just cut a 400cell cat in half and proclaim it to be a sports cat. On top of that, Its the various pressious metals that do the catalyst conversion and unless the fewer cells have a decent amount of said metals, typically 20 grams or more, you will get an EML when you "give it some" as the cat wont be able to convert the gasses efficently enough. The Ebay jobbies are certianly worth a go, as said, some seem to work quite well, but weather your getting any performance increase from them or weather thay will keep the dredded EML at bay is another thing. Ask yourself this, If there any good, why dosent the likes of miltek, blueflame, regal, etc sell the cheaper ebay varients? Id does make you think, but then again, Like vocky and others, they havent had any trouble and would apear to show resonable gains? i guess you pays your money and takes your chance.