ok....i bought a header for my new 5sfe and was wonderin if it would make a noticeable diff. to remove the lower o2 and plug it....how would it make my car run?

I have to leave mine unplugged.. its suppose to read after a cat and since its not, it would throw a check engine light.

I was under the impression that if you did leave it unplugged it would cause the CEL? I left mine plugged in without any CEL.

when I installed my header, first I had the top one in and the bottom plugged.. no CEL.. then figured the engine was running rich etc.. so got a 2nd O2 to put in second plug.. as soon as I did, 10 mins of driving CEL comes on.. so I unplug it and plug it shut.. no CEL..

my guess is that the second O2 sensor is reading like: signal = problem.. no signal = fine.. so i've run without 2nd O2 for about 5 months with no CEL...