I used a 50 states magnaflow. Also I remembered the first cause of getting this cause was a vacuum leek. corrected this and itn it's been 2 weeks without any codes. was throwing me also a 320 code. we corrected. and when we tried to pass smog test. I was told it did not turn 2 monitors to run it. also has a brand new timing belt, tensioner bearing and water pump. this last just for maintanence pourpuses. also I tuned thje engine. the only thing not replaced is the oxygen sensor, as my friends scanner, a matco, told me it was between normal parameters.