Quick o2 clamp question.
 

So I sucked it up and attempted to make my own o2 calmp thanks to the "o2 clamp for dummies" thread. Now, which o2 sensor wire do I cut into on my 99? I've seen this question answered for the NA's, but nothing on the NB's.

In my ignorant and uninformed opinion, clamp both o2 sensors' wires.

Cut into the sensor wire from the O2 sensor that is furthest forward.

i know it is the upstream o2 that you cut into, but, which wire, being I think the newer models have 4 wire o2's as the olders have 1 wire

Bosch 4 wire sensor:
2 x white - heater power & heater ground, no polarity
1 x gray - o2 signal ground reference
1 x black - o2 signal +

Those are the wires from the sensor. I have no idea what they do at the car's side of the harness. You'd be well served looking up your car's wiring diagram.

Thanks ben, looks like that might be my only choice