[Batman]

On a stock or mildly modified car high flow cats are plenty. You can tune out the rear O2's and the car will make more power but you are going to lose a good chunk of fuel mileage in the process. I would get a good set of highflow cats (Magnaflow!). The power difference over straight pipe will be negligible and you won't lose 4 MPG in the process. Plus, living in NY, if you get caught here without them and your address is a NY address they are going to rape you with tickets because by law if you change your address or buy a car out of state, then go to another state you have to register and insepect your car in that state, if memory serves, within 90 days. Not worth the risk IMO, especially when high flow CATS are just about as good.