Hollowed out Cats?

[bigred90gt]

You should have a set of o2 sensors before and after your cats, threaded into the bungs on your h pipe. It would be the same as running an off road pipe, and you would need MIL eliminators to keep your check engine light from coming on. You can get a set of the splice in ones from PEP (http://www.ponyexpressperformance.com/index.html), or you could opt for the easier, but more expensive, ones that you plug in between your sensor and the harness. I personally made mine from a diagram and instructions on a website. It cost me all of about $10 in electronic parts from radio shack (aside from the $10 soldering iron I bought). I will see if I can find that site again. If so, I'll post a link. It was rather easy to do. I took pics, but when my computer crashed, I lost them.