It just monitors temp.

 

Our exhaust systems go like this: heads, exhaust manifolds, downpipe, cat, resonator, muffler/s. Resonator is NEVER a code word for the cat. If you remove the cat, you will need to get either an O2 simulator or a tuned PCM that ignores the second O2 sensor.

 

what's the o2 simulator? I've never heard of such a thing

 

The "official" name is "O2 emulator". What it does is it fools the PCM into thinking that there is a rear O2 sensor that is performing perfectly fine. Here's one example of one: ZZ Performance

Even though it doesn't list any 5th gen Montes, I have one on my Monte and it's a 1998 so if you want one you will be okay. My O2 emulator is about 5 years old too, and it was cheaper back then too

 

So if the cats removed and the 02 is still in exhaust, it should only throw check engine light and not affect performance or mpg?

 

It's not supposed to effect performance, but you will get a check engine light. If Minnesota has vehicle inspections then that will be a problem. And like I mentioned before, there are ways to get rid of the CEL.

 

Thanks for all the info guys

 

Glad we got that confusion sorted out haha

 

I thought that was the muffler