I noticed you said your CEL light is coming on! I have the same problem (I'm running the same exhaust system) This problem will be gone once kpro is tuned, but just out of curiosity, were is the secondary 02 sensor port on your headers? i can only see one? (mine has two side by side before the cat, then 1 after the cat, although i couldn't reach the one after the cat so mine are sitting side by side atm)