I was pulled by the same cop 3 times in a month, he told me each time to get it fixed, the third time he took my license plates and towed my car. Its up to officer discretion, i think he was having a bad month or something nobody else seemed to have a problem. The first time he heard it, the second two times he just recognized my car, and pulled me. Then the setup was mac or h pipe, and weld in 40 series flows.