I installed a new Ex. man and downtube, and removed my cat. The O2 sensor hole was located atop the old manifold. I replaced it with an older manifold that had no O2 hole, so I had to get the downtubes with the hole. The O2 sensor wires weren't long enough, so I lengthened them. I think the car is running a little rich now. I just wondered if anyone else has experience with this. I remember reading that if you lengthen the wires, you have to use hard aluminum wires like what you would find in a gas grill igniter kit. I had some laying around, but only enuff to do two wires. I used copper on the third wire.