Well, got the exhaust flanges lined up and bolted together Thursday night, with the help of a large metal hose clamp and a stubby combination wrench. No apparent exhaust leaks, YAY! Unfortunately, the X runs exactly the same way it did before.
CEL still on. I haven't attempted to clear or rerun the codes. I will rerun them, but not expecting to see anything new.
Hats off to those who had said it wasn't the CAT; but, I didn't spend much money, and at least now I know for pretty much sure that I can look elsewhere. Other possible culprits, as I understand it:
1. After-CAT A/F sensors (ordered, arriving early next week)
2. MAF sensor (ordered, arriving early next week) (Ordered the $25 eBay version, will see how that goes. They're $200 - $300 at the parts stores. Absurd!)
3. Vacuum leak - don't hear any, can't find any. So far haven't even found a vacuum hose to plug my gauge into.
4. VANOS - is this the same as "Engine Variable Valve Timing (VVT) Solenoid"? I find it listed at Advance Auto for $135, and $109 with a code. A filter gasket I guess goes with it, I can get for $22. Is this the big solenoid looking thing that sits on top of the engine, kinda in between some of the coils/spark plugs? Anyone know if it as simple as unbolting and remove & replace? Advance has a video showing one all gunked up with metal bits. Maybe I could clean it out, but at that price, I wouldn't mind replacing if it is a fairly direct process.