Originally Posted by
BCS_ZHP
Ok, think this one backwards. 0175 & 0172 state burning too rich, so have you done anything that could possibly be restricting airflow? If so then you're not getting enough air to mix with the fuel on hand & the ECU thinks it's burning rich. If not and you still have the stock air cleaner with these headers then I think that's the problem. Add a CAI which will deliver more air and see if corrects the 75 & 72 codes. When you make an engine exhaust itself better, you have to also make it breath better too.