Cat removal (First post)

[grimy]

Hi guys this is my first time posting here but I read through some posts earlier. You seem to be well informed on mods to your F-bodies. I've had a SES light on for a while so I took my T/A to autozone and had them run their scantool on it. It came back with catalyst below threshold on bank2. The guys there didn't know what it was and neither did I so I took it do a dealer. They told me the right cat was bad. And wanted over $500 just for the GM cat, not counting labor.
I now live in a county that does not require emission testing. So I was thinking of just getting rid of the cats. Do I need to get something to fool the computer into thinking that I am running cats if I do this? While I'm at it I want to get a different muffler(something a little louder). Is their a big difference between buying a cat back or just buying a muffler and having a shop bend some tube for me? I read through some of the earlier posts on the cat backs but still haven't made up my mind on which one I want. I saw that some of you have taken the cats off but obd2 appearantly has sensors for them. Also are there any fit issues on installing a cat back if you don't have cats?

Sorry the post is so long.

Thanks,
Jim

[N20LT4Bird]

I would first check the rear O2 sensors, maybe they can do it at autozone again? Check to see that the 2nd O2 (downstream) is mirroring the upstream O2 (with a little delay) on that bank. If the downstream O2 is not functioning right, it will throw the code, and the CAT may be fine.

The right way to fix the CAT is to get another one. Even though your state doesnt do a tailpipe "sniffer" test, they probably do a visual check to see if the components are removed. If you wanted the inexpensive way out, you could hollow the CAT out (so it still looks like its there) and put in O2 sims, or have the computer reprogrammed without the downstream sensors (and add some performance programming too! ) The removal of the CAT WILL throw a code otherwise.

[mstg-etr]

cat removal

Hey Grimy,
A cat back system has no muffler. It is straight pipe from the catalitic convertor, usually larger than stock, all the way back to the rear end of the car. Thus the name cat-back.
I would suggest installing a cat back system. You can get them with the cats...and a lot cheaper than $500 a cat.
A 3" cat back system will usually increase your HP by about 20. It will also give you that deeper sound you are seeking. It may be a bit too much for the average driver. It will give you goosebumps the first time you hear and feel it in your own car.
You won't have to change any computer settings for the cat back system.
If you travel at all in your car you will want to have the catalitic convertor in place to avoid costly fines, not to mention it is better for the atmosphere.
Check out a Borla system. There are lots of other good dealers too.
Jeff

[Jeff_in_Atl]

I have a sugestion, try swithing the rear O@ sensors and see if the SES code switches banks. If it does, it's the O2 sensor. If it doesn't, It's the converter. I kind of doubt the converter is bad.

[Injuneer]

Re: cat removal

Originally posted by mstg-etr
Hey Grimy,
A cat back system has no muffler. It is straight pipe from the catalitic convertor, usually larger than stock, all the way back to the rear end of the car. Thus the name cat-back......

I would suggest installing a cat back system. You can get them with the cats...and a lot cheaper than $500 a cat.....

Jeff

Some misleading info in this post.

A "cat-back" is a full replacement exhaust system for everything from right AFTER the catalytic convertor, to the exhaust tips. It almost ALWAYS includes a "muffler" of some sort. I've had a Borla 3" adjustable cat-back - it included a muffler. I've had a Mufflex 4" cat-back - it included a muffler. Even the SLP "Loudmouth" which appears to be all pipe, and no conventional muffler, inlcudes a noise reduction "chambered" section. So.... generally a cat-back for a 4th Gen LT1 will include a 3" intermediate pipe, a muffler of some sort, and tips.... maybe dual tips, maybe a single tip, etc. There are systems with 3-1/2" and 4" intermediate pipes also.

And, since a "cat-back" is by definition everything AFTER the catalytic convertor, it isn't going to be supplied "with the cats". The stock 4th Gen LT1 dual cat exhaust sytem includes a cat on the drivers side that is right up against the drivers side exhaust manifold - no where near the "cat-back". To get high flow cats, you typically buy a new Y-pipe, with the dual high flow cats included. Or you can replace just the stock cats with high flow aftermarket cats. But a "cat" doesn't come with a "cat-back" system.

[Jay 02 TA ws6]

Originally posted by N20LT4Bird
I would first check the rear O2 sensors, maybe they can do it at autozone again? Check to see that the 2nd O2 (downstream) is mirroring the upstream O2 (with a little delay) on that bank. If the downstream O2 is not functioning right, it will throw the code, and the CAT may be fine.

The right way to fix the CAT is to get another one. Even though your state doesnt do a tailpipe "sniffer" test, they probably do a visual check to see if the components are removed. If you wanted the inexpensive way out, you could hollow the CAT out (so it still looks like its there) and put in O2 sims, or have the computer reprogrammed without the downstream sensors (and add some performance programming too! ) The removal of the CAT WILL throw a code otherwise.

You guys just don't get it!

Some states have NO INSPECTIONS whatsoever! Michigan is one, and I believe Indiana is another.

[N20LT4Bird]

Okay Okay already. You made your point. Its just that I hear people say things like this in upstate NY all the time. People think they can tear the emissions off a car becasue there isnt a sniffer test. But, they still fail for missing the components. I dont have a list of every state in the union and their inspection criteria, so I figured I'd post a warning.

By the way, you guys are lucky. Big brother isnt watching over your shoulder telling you how you can mod your car. Must be nice

[MN6WS6]

Yup, no inspections here either. A legal exhaust is defined as headers with mufflers, so we have guys driving drag cars on ET Streets (and sometimes slicks if they're really brave) with headers and twist-on mufflers.

My 96 WS6 has a "significantly modified" exhaust system

[Jay 02 TA ws6]

Originally posted by N20LT4Bird
Okay Okay already. You made your point. Its just that I hear people say things like this in upstate NY all the time. People think they can tear the emissions off a car becasue there isnt a sniffer test. But, they still fail for missing the components. I dont have a list of every state in the union and their inspection criteria, so I figured I'd post a warning.

By the way, you guys are lucky. Big brother isnt watching over your shoulder telling you how you can mod your car. Must be nice

I was just giving you a hard time.

[N20LT4Bird]

Originally posted by Jay 02 TA ws6
I was just giving you a hard time.

I know. Me too.

[TraceZ]

No regs in Wisconsin. I had my car shipped here from Texas. The state isnt even interested in seeing the car. I filled out the paperwork, wrote a check and was on my way. It could be converted to a jet dragracer for all they care.... The title matches the VIN and the plates, that is *all* that matters.


Now... having said this, I still would not remove any smog equipment from my car. Rules may some day change, or I might sell the car. If it does not meet smog, I wont be able to sell it to someone living in a testing state. This would hurt the value of the car. Not only that, but dealers wont accept trade-ins that are stripped of smog equipment.

I am interseted in preserving my investment in my car. Your car may be different. You might not care about its future value. Your interests might be different than mine.

[grimy]

Thanks for all the replies. I did some more reading on this forum, and found that removing the cats may make the exhaust sound a lot louder and increase the pitch some. So I'm thinking of either buying a y-pipe with cats or 2 new high flow cats. Any suggestions on either one(brands and a place to buy them from)? Also, I think I'm going to get the Corsa cat back. Anyone know where I can find the best price on this? And Indiana has 4 counties were they do emission testing, in those 4 counties they do a visual and performance(sniffer) test. I used to live in one of those counties but have since moved to a county were they have no testing at all.

[Kevin - Blown 95 TA]

Originally posted by TraceZ
No regs in Wisconsin. I had my car shipped here from Texas. The state isnt even interested in seeing the car. I filled out the paperwork, wrote a check and was on my way. It could be converted to a jet dragracer for all they care.... The title matches the VIN and the plates, that is *all* that matters...

Wrong. Depends what county you are in. In SE Wisconsin, they are very strict with a visual inspection and IM240 test - dyno for the OBD1 cars and computer check for OBD2. They even check cars 25-30 years old.

[TraceZ]

Originally posted by Kevin - Blown 95 TA
Wrong. Depends what county you are in. In SE Wisconsin, they are very strict with a visual inspection and IM240 test - dyno for the OBD1 cars and computer check for OBD2. They even check cars 25-30 years old.

I had heard something about Milwaukee tessting a long time ago, but never knew for sure. You just confirmed it. Do you know the exact counties?

Anyhow, in Madison (the most tree hugging city in the country) we get off scott free. The *only* time you would have a car tested for any functionality is:

A: you are taking a drivers test in it

B: it had a salvage title and you were puting it back on the road after fixing it

And.. they *still* wouldnt check emissions, just the horn and lights and apparent roadworthiness.