I am not sure what your guys laws are. But where i live (Canada) it is illegal for me to take the cat out of my exhaust system. Even though i don't need emission anymore the car was produced with a cat and as the law states, for the car to be legally run you need all the parts that came with your car to be on it. So for me i need a cat, because if i get pulled over and they check it. I get slammed with a ticket :O