Do i need a new O2 sensor?

[undrcroft]

92 camry 4cyl. Just upgraded the headers. when i took out the o2 sensor it had a good bit of carbon covering it. The check engine light isn't staying on, but should i change it anyway for better performance? not just Hp but gas mileage and all that. Is there a good place to get an O2 sensor besides the parts store? Or should i just get a cheap-o one? Does it really matter how good it is, and if so where is a place online that sells really good ones?

[Nico]

O2 sensors on Camries generally don't have to be changed that often. I did it on mine as I had some problems which actually turned out to be compression problems. Even if it is a bit dark, it is alright, provided it isn't completely burnt.
I am not a professional in that matter and probably other people would have a different opinion about it but this is definitely not the kind of part I would modify or replace by another one, 1° because I would doubt very much that this could lead to better performance and 2° because it could possibly cause a few problems afterwards with the ignition.
But this is only my opinion...