You can get used sensors from www.sohfast.com.

The wiring is likely already there, you just need to put them in a place where the O2 sensor wiring will meet up with the connections on the car. What kind of header is on the car?

 

headers are dc sport 4-2-1
I dont know if the wires are already ther but i can see the harnesses unplugged

 

A DC header has a bung in it. Is it just open or is there a plug in it? If you can see unplugged harnesses, those are the wires. The O2 sensors (factory ones) will have the other part of those harnesses and wires on them so they will plug right in.

 

one more question
how about the second o2 sensor where is that one located at?

 

The first is on the very back of the header where it meets with the rest of the exhaust (usually the OEM CAT). The second goes into the CAT which (from the factory) is located just behind the vertical position of the firewall. It's hard to type out. You should see the hole with the rubber grommet and the harness hanging down (unless the other guy pushed the harness up into the gromet).

 

Will not get it inspected