O2 sensor trick/CEL help for 04 Reno/Optra5

[nk403]

After struggling to put in a test-pipe I decided to take my car into the muffler shop to get a quote for a custom exhaust (from before the primary CAT-that is, the CAT before the exhaust) with the test-pipe install. I actually was thinking of doing a full custom exhaust, but the guy at the shop said that it would be expensive (although he didn't say how much). He was saying that the drawback of going that way was the CEL would be tripped. He started saying "we don't do that" when I started to ask him about the CEL trick- until he figured out that I only wanted a bung installed to which he replied "Yeah, we can do that" as he wrote on his clipboard. He said the hole for the sensor needed to be after the primary CAT (the one that would be upgraded).

Here is what I know: I can have a bung installed wherever the stock O2 sensor was or right after where the new one will be. What would be the limiting factor given the length of the O2 sensor cable and where it plugs in the mid-pipe from the factory? Instead of the non fouler trick couldn't I just get a longer bung for the O2 sensor after the CAT? Is it one inch- or is it one inch plus the length of the existing bung (which I don't know)?


Any help is greatly appreciated. Thanks in advance. Sorry for sounding like a math problem.

[7-even]

the non fouler isnt just a longer piece in between the exhaust and the o2 sensor. it has a very small hole in the end of it so the o2 sensor is only reading a very small portion of the exhaust flow instead of the full amount its supposed to. by only being exposed to a portion of the flow you hope to trick the sensor into thinking that everything is ok. our car has 2 sensors (one after each cat) so if your going to do a full exhaust you would need 2 of them

[exist3nce]

Originally Posted by 7-even

our car has 2 sensors (one after each cat) so if your going to do a full exhaust you would need 2 of them

not quite. The primary O2 is in the exhaust manifold before the first cat. The second is around the middle of the car after the second cat. The purpose of the primary O2 is to control air/fuel ratio, and the secondary monitors the condition of the cats.

[nk403]

So I got a quote for 1000CND for a custom exhaust (incl. Magnaflow muffler, CAT that's not Magnaflow, labour, 2.5" piping, test-pipe install) from the primary CAT onward. Isn't that a tad steep? I wasn't too sure what type of muffler and CAT I'm getting either. I'm 90 percent sure the quality of components would be better going through Kinky, though. So for the same price I could pay for labour and questionable parts or better quality components that have actually been tested on our car and do it DIY (like I've been doing so far). I guess I have to talk to Kinkyllamma/Danny.
Thanks for the help so far.