Just put on a new exhaust, cat, headers, o2 sensors because my car failed emmisions. Now it failed again. Its a 95 z28. plugs and wires have about 15k miles on tem if that. Any ideas?

edit. the new exhaust consists of mac headers, magnaflow high flow cat, and slp loudmouth exhaust.

 

What part are you failing?

 

he said nox it sound like

 

Correct me if I'm wrong somebody, but isnt nox directly effected by converter operation? Or is it too cool an exhaust, maybe the converter needs to get hotter? I'm sorry but for this I'll have to let someone else answer you correctly.

We're lucky here and don't have emissions testing.

Did they do a running roller type, or just hook up the exhaust pipes?