I didn't have to remove a cat or extend the o2 wire on my '97 Tib 5speed. I got the 421 headers and they are GREAT!

Rich.

 

Yes, you did. There is an upfront vertical cat included with the stock exhaust manifold. If you removed the stock exhaust manifold, you removed the front cat. You also have 2 o2 sensors, not just one. The wires for the first o2 sensor are not long enough to reach under the car, so if you did not extend the wiring to reach under the car, you are only sniffing 1 or 2 cylinders...depending on where you installed the o2 sensor.