Bassani makes two of each Y-pipe for each engine configuration as far as I can tell. The Y-pipe with the CAT is a seperate part number from the one without. Missouri emmission laws are just as stringent as MA and I pass with no problems. There was never any sort of "pre cat" on mine. I know people say that the larger diameter bulge in the stock Y-pipe is some sort of "cat-type" device but when I cut the old stock Y-pipe down I cut right through the middle of that part....there was NOTHING in there. Besides, without the air injection from the smog pump any catalytic converter mounted further forward than the air injection barb would overheat and melt itslef into oblivion! Say what you will but the idea of two cats (one behind the other) is a redundancy. Two cats on true duals well, yeah, that makes sense. The Bassani Y-pipe that ISN'T emmission legal has no CAT at all. Its made for racing juts as they claim on the site.