Yeah same deal with me too.....I already had a hard ass time with my headers about a week ago...now I have a high flow cat...and that was a ***** with the O2 sensor and the ****ing 3 nuts on the rear end of the cat....I had to use a damn hacksaw to cut off 2 bolts while it was still connected to the car (it hung down a bit). So then I get the damn cat off...now I dont have a metric open end wrench...but i took off the O2 on the headers with it...well STRIPPED!!...luckily I had one end left on the sensor so I took a propane torch to it and some brake cleaner, WD40, silicone lub and all sorts of other ****....and it didnt budge...then I tried one more time and it came out nice....now I got it in but the O2 sensor wire is not long enough because it is on the forward side of the cat..so I had to extend the wires with some connectors....but now if ****ing have the CHECK ENGINE light on now!!..im so irritated of this ****....
just thought I'd share that with you

 

Reminds me of putting an exhaust on my friends 90 sierra. Took us 5-6 hours to pull the old rusted to **** one off. Took 30 mins to hook up the new one. Now that I think of it that was my first mod install. Where does the time go?