[Unichip Jack]

Thanks for the posts.

enwave… spot on, thanks… although “completely” is more accurate than “technically.” As he says, we are and have been in e85 discussions with the EPA; we just spoke with them again this morning.

Rough running after installing a header isn’t a “tuning” issue… the header’s impact on an airflow based tune is actually pretty minor. It is an emissions issue.

It's not even really the header per se, if you use the same header with a cat (with a stock front pipe cat) you won’t have a problem. That’s why the header companies recommend you keep the cat.

Unfortunately, when you delete one or both cats, the OEM ECU quickly declares a cat efficiency fault (which all street legal vehicles must do) that results in a CEL and poor performance on some vehicles.

Beyond the timing and fueling changes for a header with cat, what the “no cat tune” does is turn off the cat code. Only problem is that’s completely illegal and what cost Edge Products better than 7-figures in fines and penalties… http://www.dieselnet.com/news/2013/01epa.php.

If you use an O2 spacer or spark plug non-fouler on the downstream O2 sensor port, you’ll avoid the fault code and should be golden.

Cheers