You don't have to have the catalytic converter been running mine without one for about 70 75,000 miles it does make it a little louder also running the magna flow muffler but there's many that just straight pipe it no muffler no catalytic converter your choice personally I would recommend taking the catalytic converter off and leaving it off it just accumulates a bunch of sut and create more back pressure than what you need mine runs much better once I took it off more power little better mileage
