Sure, I got rid of mine. Three options I can think of that you have are 1- if you have inspections (which I assume you do, being in Chicago) you can gut them, and put a straight pipe through it. I think aussi knows about this
or 2- Cut the cat out and put a straight pipe in it's place or 3- Get a cheaper cat to replace it ($500 is alot for a cat) If you decide to get rid of it, yes, you can expect a power gain and a louder and sometimes more raspy sound... -Nick
