Exhaust work on 924S - New Catalytic converter and muffler

After passing Smog testing consistently for years, the red car finally needed attention -- it failed smog at a couple of different test sites. "Guarantee to Pass" fuel additive didn't work and neither did changing the oil, oil-filter, air filter and spark plugs.

NOx value suddenly spiked, and I also smelled fuel intermittently inside the car.
I'm not sure if the two are related at this point. After Catalytic converter replacement, I have not smelled fuel yet. The NOx levels fell to 0 an 42 ppm at 1700 and 2800 RPM respectively.

Being a Wisconsin car previously, the 87' 924s, now affectionally known as "Big Red", had some serious corrosion on it's muffler and around the Catalytic converter. These issues were in addition to the fundamental failure of CA Smog testing.

-> I was unable to remove the O2 sensor from the exhaust pipe. It had essentially corroded on. Later, I would have an exhaust shop (Kwik Way in Santa Clara) cut out the sensor threaded nut with a plasma cutter and weld another onto the pipe with a MIG welder.

-> I removed the exhaust from the header pipes and saved the gaskets. Some bolts broke along the way, but Bob at Kwik Way was able to provide replacements without too much difficulty. I also had him order the new Magnaflow Catalytic converter.

-> I went to Pick-n-Pull Oakland to get a replacement muffler from an 86' 944. Bob welded it to the rest of my exhaust in place of my existing rusty muffler.

I'm now able to drive her over Thanksgiving break! Only two remaining issues to address:
-> Exhaust vibration at 3800 RPM as I think the Exhaust is resonating against the Catalytic converter heat shield at that frequency.
-> Oil Pan Gasket replacement. This one will take about 8-10 hours+ according to Clark's Garage
This job will require removing the suspension drop link while supporting the engine from above!