I doubt it would pass any states emissions inspection-just be prepared to reinstall stock parts for inspection. another option, though costly, is to put a Random Tech cat in-it is the final touch for a complete high flow exhaust system. Comparing it with the stock cat, well ther's just no comparing the two. It will definately add some power and along with a shorty header they work together to really free up the exhaust flow. Money is always a consideration, but there is so much you can do to get more power without compromising emissions.