So I am not finding any answers on my kia forums so I thought I would ask you guys. Besides owning a 91 crx HF I also own a 2005 Kia spectra 5. I recently bought a header and midpipe for the car. After waiting 5 months I finally get it. The stock setup was as follows: Exhaust manifold with 1st 02 sensor, catalytic converter, downpipe, midpipe with Flex part and after that 2nd 02 sensor, cat, resonator, more pipe and muffler. The header and midpipe eliminated both of the cats. Not only was this freakishly loud, but it is also now throwing a P0420 code. I was advised to buy an 02 extender off of ebay. It costs $9 and $4 to ship. Needless to say it is crap and does not do anything. It may work for your car but it did not work for mine. I already had my stock cat welded back onto a section of the midpipe closer than it was during stock configuration but it is still behind the 2nd 02. What I am going to do now is go to the same exhaust shop and have them drill a 02 bung behind the cat. Then I will ahve to cut and splice in more wire to physically extend the 2nd 02 sensor BEHIND the cat. I was told that the distance matters by some and that it doesn't matter if it is right behind by others. Anyways I will see what the shop says. My question is this: what care should I take when extending the wires? I already have the correct gauge wire, and I am going to solder and heat shrink the wires to give a good connection, but is there anything else I should worry about? I mean has anybody that owns a Honda ever had a P0420 code thrown for something like this? What did you do? Thank you all for reading.