Cats..what to do?

**Guerrillakilla13** · 11-19-2012, 10:55 AM

I have a new problem, yet again

My SES light has been on for a few months now, and the code it throws out suggests that my drivers side cat went bad. Well just recently, I noticed that my exaust fumes smell more strongly like gasoline than before.. like 'I have an offroad Y pipe' bad. On top of that, at idle i've also noticed recently that there's alot of chatter and rattling coming from my engine bay sometimes; I'm pretty sure that's the cat as well. So I have a few quick questions

Would it be more efficient to replace both my cats with high flows, or just buy a stock cat and replace?..
If i bought high flows, would I noticed a volume increase? performance increase? even if just the slightest bit..

I'm currently not looking for LT's anymore since I've been financially raped lately, so that's out of the picture for now. Any personal suggestions on what I should do? Thanks alot everyone

**bigrondownhiller** · 11-19-2012, 12:54 PM

What is the code exactly?

**pajeff02** · 11-19-2012, 03:12 PM

If you are interested, I have stock GM warranty replacement cats sitting in my lower garage. I think they have around 15,000 - 20,000 miles on them based upon the vehicle's warranty service history. Replacement high flow cats will probably require some fabrication for installation, unless you go with a direct fit aftermarket unit from the parts store.

**2002ssslp** · 11-19-2012, 04:16 PM

I would go with the LTH and the high flow cats. They will give you better throttle response, Better MGP and more rwhp. Go for it.

**Guerrillakilla13** · 11-19-2012, 04:34 PM

bigron If I recall correctly it was P0420..

Pajeff how much do you want for them man? I was thinking of buying used but I don't want to get F'd by them again, my car only has 50k miles and my cats already went bad..

Keith I don't have the money to do a LTH and Upgraded Y pipe install unfortunately. Otherwise I would.

**az gt eater** · 11-19-2012, 05:15 PM

That's too bad, I just sold mine a few months back. I think I got 200 for the pair. Oh well. Sounds like Jeff is your best bet. I hear that the high flows don't last as long as the factory ones. They are pretty easy to change. Just soak the sh*t out of the bolts the night before.

**pajeff02** · 11-19-2012, 05:19 PM

Honestly, they are just taking up space in my garage, so $50 each plus shipping. Not sure how much that will be though as they do have some weight to them. Here's a pic of the driver side cat still attached to the manifold that was taken during the header install project:

**cammed goat** · 11-19-2012, 06:42 PM

Grab the ones from Jeff. I could only imagine how much factory replacements would be from the dealer.

**az gt eater** · 11-20-2012, 07:31 AM

Originally Posted by cammed goat

Grab the ones from Jeff. I could only imagine how much factory replacements would be from the dealer.

I agree, smoking deal. Jeff could get double that from a salvager. He is def doing you a favor.

**Guerrillakilla13** · 11-20-2012, 01:04 PM

lol looks like youre my best option Jeff. Find out how much shipping is and I'll probably take the drivers side off your hands..Thanks a lot for the offer man I do appreciate it.

Is installing stock cats as easy as soaking the bolts overnight with WD40and than taking it off? I don't have to mess with sensors or remove the battery or do anything like that do I?

**pajeff02** · 11-20-2012, 05:12 PM

Depends on how bad things are rusted up. If they don't break free, try a little fire on them. Even a propane torch can be enough to break a stuck nut or bolt free. PM me an address and I'll get it pulled apart tomorrow and checked out for shipping. May not make it to the PO until Monday though as we are traveling for the holidays.

**2002ssslp** · 11-22-2012, 07:40 AM

Originally Posted by az gt eater

That's too bad, I just sold mine a few months back. I think I got 200 for the pair. Oh well. Sounds like Jeff is your best bet. I hear that the high flows don't last as long as the factory ones. They are pretty easy to change. Just soak the sh*t out of the bolts the night before.

PB Blaster works best for me.

**2002ssslp** · 11-22-2012, 07:44 AM

Originally Posted by pajeff02

Honestly, they are just taking up space in my garage, so $50 each plus shipping. Not sure how much that will be though as they do have some weight to them. Here's a pic of the driver side cat still attached to the manifold that was taken during the header install project:

When you look at the cost of a factory OEM exhaust manifold and the cost of a decent header, why wouldn't GM just use headers ? Manifolds are sand cast and take more work to make then the bent tube headers.

**Guerrillakilla13** · 11-24-2012, 12:37 PM

lol i'll try the torch thing as a last resort, PB blaster sounds worthy of trying.

**az gt eater** · 11-24-2012, 07:44 PM

PB works. That's what I used.

**SS Camaro UK** · 12-02-2012, 04:54 AM

Originally Posted by 2002ssslp

I would go with the LTH and the high flow cats. They will give you better throttle response, Better MGP and more rwhp. Go for it.

Is it true that LTH's will give better gas mileage? That would be another great reason to get some fitted, especially with the cost of fuel where I live.

**Guerrillakilla13** · 12-07-2012, 11:41 AM

Originally Posted by SS Camaro UK

Is it true that LTH's will give better gas mileage? That would be another great reason to get some fitted, especially with the cost of fuel where I live.

They're supposed to, by at least 1-2 mpg so I've heard. It's great and i'd love to have em but I just can't dish out over a grand for something like this.

BTW in case anybody has been wondering, A bad cat makes the exhuast sound so sexy. The borla i have makes a clean idle sound, but with the cat going bad it sounds like its cammed or something hahaha

**Guerrillakilla13** · 12-09-2012, 10:34 PM

Sorry to resurrect but I figured I'd ask..should I replace the sensor of the cat while I'm at it? Is it necessary? And if so is it a pain in the arse to do?

**pajeff02** · 12-10-2012, 03:22 AM

I would only replace the downstream O2 sensor if it is throwing a code after you replace the cat. They're easy to get to and no sense spending $$ on something that doesn't affect how your car runs. The upstream O2 senders should be replaced in the 75,000 mile range -- unless they are throwing codes or their output is sluggish.

**Too Fast** · 12-10-2012, 03:36 PM

What Jeff said. Only replace the downstream O2 if it has a code saying it is bad. And no, it isn't hard to do as long as it's not seized. You have to take it out and put it in the new converter anyway, if you get a ''direct fit'' converter. And use some rust penetrant on the O2, before you take it out; if you have some, use a small amount of anti-seize on the threads of the O2 sensor before you install it.