I've got a 97 gsr and I wanna put in a test pipe and not get the cel. Couldn't I simply disconnect the second o2 sensor and hook the wires to the first o2. The reason I say this is the first o2 is in the headers so that's unaffected by the cat and the second one just causes a cel if there is a difference from the first one. Just an idea, let me know what u think.

 

I think its the other way around. If the 2 sensors read the same thing, you'll get a CEL. The catalyst 'uses up' the oxygen, so the ECM is expecting to see a difference between the 2 readings.

 

i was running a test pipe on my 97 gsr they sell pipe with two inlets for both your sensors, but becareful not to burn the wires of one, cause thats what happen to me the sensor wires touched the testpipe which melts it when is hot, it happen and caused a big short, so be careful.
testpipe.com

 

I'm running a test pipe w/ 2 o2 sensor inlets, i've been w/ no cel for about 8 months now, and it dosent look like im gonna get one.
THe only precaution I would take is being careful of not buring the wires of one of the o2 sensors like LSVTEC408 said.