Originally Posted by BLM

In terms of construction, the best way to avoid a CEL with a TP or HFC is to have an extended, right angle O2 bung (to prevent the O2 sensor from being in direct contact with exhaust gases that have either passed through a HFC or cat-less TP) as is seen with

Fast Intentions:





and, GTM:





ERZ/CNT has the best pricing and members say the quality is good with low incidence of CEL's but the pictures I've seen don't show a right angle bung, though it is extended. In terms of steel wool, you actually shove a ball of tightly packed steel wool down into the O2 sensor bung before you re-attach the O2 sensor to your aftermarket TP/HFC. This is reported to work, but the right angle O2 design of GTM and FI works as well. In addition, if you choose to go the route of short headers +/- TP, you might eventually get a CEL, which can be eliminated with an UpRev tune as stated above. With Long Tube headers you'll need a tune anyway to get the most out of them.