After I installed my Xpipe I installed MIL eliminators that I had made. They did not work so I took them apart and remade them. Still did not work so I bought new parts and remade a new set. They still did not work so I thought I was going to have to order a pair from American muscle. Then I saw a post from someone that used 18 mm non fouler plugs. For 3.99 plus tax I solved my service engine light issue. It is really easy to do. Just go to your local auto parts store and ask them for 18mm non fouler plugs, they come two to a pack. Take them home and drill them out with a 1/2 drill bit so the O2 sensor will fit in them. Unhook the negative battery cable to clear the code if you don't have the tool to clear codes.Jack up you mustang remove your rear O2 sensors. Screw the non fouler plug in where the O2 sensor came out and reinstall your O2 sensors. It moves the O2 sensor back out of the fumes so it thinks the cats are there. Hook your battery cable back up and you should be good to go. If for some reason it still gives you a code buy another set of 18mm non fouler plugs and add them to the other ones to move the O2 sensors back further out of the fumes.