A spoof will be caught in an emissions test. They are also most commonly used when people delete or gut the cat.

I believe that'* incorrect. O2 spoofs are illegal. Period.

Will, I understand how vehemently you are opposed to foul emissions. I wasn't trying to say that using a spoof is within the law. I'm merely pointing out that a hi-flow cat may flow a little more uncatalyzed exhaust than a stock cat. The sensor may trip a code because it detects more pollution than stock, but you might still be able to pass an emissions test. See what I'm saying? I'm not trying to debate the technicalities of the law, I'm just saying that as long as you're not putting more pollutants into the air than the law allows you're right as rain, legally speaking. I figure as long as you're within federal or state limits, who cares whether the PCM needs to be pacified? Of course I say all this assuming that PCM tolerances don't coincide with federal regulations. I'm assuming that pollution levels that may be unacceptable to a sensor and computer may still be good enough for a police sniffer.

Gotcha, but your clarification brings up another point. According to my exhaust guy (some met him at WCBF), high-flow cats don't pollute any more than a standard cat. They just have greater surface area. In other words, they can treat more exhaust at one time than a stock cat.

I think my major point with the spoof is to make sure nobody gets caught and fined. You all know how I feel about cats

Shoot them on site?

You can get a high flow cat with a plug for the O2. No need for a spoof.

Wait so when I get my High-Flow Cat installed does that mean I'll see a Service Engine Soon light on or will it be just as it was before? Im confused.

OBD II cars cannot legally have the cat replaced by anything but an exact OEM unit. Even if you do put one that is better in there, it'* technically illegal.

Another problem with high flow cats in the OBD II chain is getting by the PCM. It doesn't take much of a difference (mabe 5%) to throw a code for a rear o2. If your new one is well within govt regs but doesn't fit the PCM, you'll fail automatically based on the light.

I'm sure there are cats that will work fine, but you gotta fit your PCM requirements and the Sniff test req'*. I can't tell you how many cats would, or wouldn't work for your application though.

So then my car is OBD II and I probably shouldnt get the cat?

Dude, You're as OBD1 as the day is long. Go for a high-flow, consider adding a resonator, make sure they use SS pipe when they install it.

Do I just tell them to add a resonator or will I have to go searching for a resonator for our cars? lol

You'll have to go searching for a resonator because I don't believe that the 93'* had one. You won't have to have an O2 spoof either because we only have one O2 sensor anyways. P.*. MY BOSCH O2 SENSOR CRAPPED OUT TODAY!!!!!! lol Made it 2 and half months on it hahahahaha....POS. Anyways.....I love MN, no emmisions anymore. Did away with those a while ago.....So in MN, you still won't find anyone to remove your cat and not replace it, but they won't hassle you about a hi-flow here (I already looked into that).