sup guys i need help to lower high nox emissions. This is the second time i failed smog after i did a tune up on my car. I passed almost everything except high nox emission in the 15mph run. I have a injen cai, stillen y-pipe, and a greddy sp exhaust. Does anyone know what could be causing these problems? i check the egr and cleaned sum carbon build up. I have no clue what do now. Any help will be greatly appreciated. Thanks