before I hack up a cable, anyone know if there are extension cables available for the 2nd o2 sensor?

My cat moved back quite a bit due to the 4:1 header, I need almost 12" more cable

 

Perhaps an electrical engineer type will chime in but I am thinking that if you went with a little larger gauge wire and soldered the joint the resistance would not be increased outside the parameter range.

With a shorter cat, the 4-2-1's do not push the O2 bung back so far that you cannot use the stock cable.

 

I don't think anyone makes an extension jumper.
You'll have to either splice in some extra wire to yours (same gauge wire is fine) or create your own juniper from a male and female plug, w/ wire, from a parts car.

 

There are two choices. Extend the body side harness or the O2 sensor harness. I would choose the former as the splices would be protected from the elements behind the heat shield, and you only do it once.