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Possibly putting the oem cats back on

Robottrainer

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Might be going back to oem cats from the gesi stuff I fabbed up to the oem headers. I had to weld on a new flange to match up flange I put on the header.

Much tig welding and massaging to get the non round cat inlet to match the flange.

How does the substrate look to you guys. If you had to do this, would you run this?

20250526_113903.jpg
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nnnnnn

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You might want to rephrase this because I read it three times and couldn't understand what you're really saying. What's wrong with the GESI cats that's making you go to OEM?

Did you weld a GESI cat substrate to OEM flange?
Or OEM substrate to just a GESI supplied flange?

Might be going back to oem cats from the gesi stuff I fabbed up to the oem headers. I had to weld on a new flange to match up flange I put on the header.

Much tig welding and massaging to get the non round cat inlet to match the flange.

How does the substrate look to you guys. If you had to do this, would you run this?

20250526_113903.jpg
 
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Robottrainer

Robottrainer

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You might want to rephrase this because I read it three times and couldn't understand what you're really saying. What's wrong with the GESI cats that's making you go to OEM?

Did you weld a GESI cat substrate to OEM flange?
Or OEM substrate to just a GESI supplied flange?
Sorry for the confusion. Cut the old cat off the manifold. Fabbed up a 3 front half with GESI cats. Got the cats to go ready. Only the O2, and heaters won't set. we don't have emissions testing...for now. That could change in the next couple of years. so I welded a flange onto the old cat in case I decide or have to go back to stock. I won't use it if it looks marginal. There are a couple of spots that look different. Just wondering more knowledge people in this matter think
 
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Robottrainer

Robottrainer

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Sorry for the confusion. Cut the old cat off the manifold. Fabbed up a 3 front half with GESI cats. Got the cats to go ready. Only the O2, and heaters won't set. we don't have emissions testing...for now. That could change in the next couple of years. so I welded a flange onto the old cat in case I decide or have to go back to stock. I won't use it if it looks marginal. There are a couple of spots that look different. Just wondering more knowledge people in this matter think
This was done to be proactive as I think with my kind of use and a Gesi cat it would be less likely to implode and cost me an engine. Cats are cheaper.
 

nnnnnn

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Normally for emissions testing, they'll stoop to the ground with their knees to bend and check. All they can see is the outside condition of the cats, not the inside and the stock ones normally don't have markings on them to my knowledge.

The flange GESI provides is for the easy swapping like you did. I'm surprised you're getting codes though from what you described, you shouldn't be getting any codes. I didn't have any codes when my GESI ones were installed. Did you get the correct GESI cat for your vehicle model year?
 

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Robottrainer

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Normally for emissions testing, they'll stoop to the ground with their knees to bend and check. All they can see is the outside condition of the cats, not the inside and the stock ones normally don't have markings on them to my knowledge.

The flange GESI provides is for the easy swapping like you did. I'm surprised you're getting codes though from what you described, you shouldn't be getting any codes. I didn't have any codes when my GESI ones were installed. Did you get the correct GESI cat for your vehicle model year?
Bought the generic 3" UHOs. I thought it might be the rest o2 location. I moved them forward. Same thing. Both banks.
 

nnnnnn

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Bought the generic 3" UHOs. I thought it might be the rest o2 location. I moved them forward. Same thing. Both banks.
If moving the O2 bongs away didn't solve it then it's the catalyst design inside the generic ones you bought most likely. What the computer of your car expects from the cats as far as behavior is not what they're doing. They may be reaching temperature too quickly, too slowly to make your computer think your O2s are failing or not be the right length or density.

To go back to your initial question though, my opinion is that as long as the outside looks good, it'll pass a visual. You can post pics of the outside too. Others may have a different opinion. I'm speaking from my experience.
 
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Robottrainer

Robottrainer

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If moving the O2 bongs away didn't solve it then it's the catalyst design inside the generic ones you bought most likely. What the computer of your car expects from the cats as far as behavior is not what they're doing. They may be reaching temperature too quickly, too slowly to make your computer think your O2s are failing or not be the right length or density.

To go back to your initial question though, my opinion is that as long as the outside looks good, it'll pass a visual. You can post pics of the outside too. Others may have a different opinion. I'm speaking from my experience.
Just trying to get the opinions of the more experienced as to whether those little marks in there appear normal before I risk using it. That, opinion wise, they look sound and if you would use it. The goal here is to return it to stock. Have a functioning cat with not hassles of codes or i/m test readiness issues.
 

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Not sure what part of Canada you’re in, but Ontario had emissions testing and got rid of it a few years ago because it was, well, bogus. I haven’t heard one iota of a lick of it returning. Never say never though.

Stocks cats are much better than aftermarket. GT500 or hellcat cats would be ideal. The GESI are made in the GTA area.
 
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Not sure what part of Canada you’re in, but Ontario had emissions testing and got rid of it a few years ago because it was, well, bogus. I haven’t heard one iota of a lick of it returning. Never say never though.

Stocks cats are much better than aftermarket. GT500 or hellcat cats would be ideal. The GESI are made in the GTA area.
Yes I know. It's not so much us not having emissions testing. It's more about the car functioning properly (check engine lights, full trims, O2 drifts). The original plan was for something more durable and less prone to failure while maintaining normal operations. This hasn't been the case. Having to re weld a flange onto to the original cat does concern me some.
 

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Ok. I thought you wrote it was coming back…

where are located?
 
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Robottrainer

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Ontario Canada
 

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Ok so you are from Ontario. Where abouts? Where did you hear emissions are coming back?
 
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Robottrainer

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Ok so you are from Ontario. Where abouts? Where did you hear emissions are coming back?
GtA. This new safety inspection stuff. Part of the inspection is emissions ready. They are hearing rumors of a safety inspection every two years.
 

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GtA. This new safety inspection stuff. Part of the inspection is emissions ready. They are hearing rumors of a safety inspection every two years.
Interesting.

I must be living under a rock. I haven’t heard anything about a new safety inspection. Unless this is the DriveOn one which is a farce. No emissions on that I don’t think. Is there?
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