Replacing Catalytic Converter

Schwamm

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2003 Mazdaspeed Protege, 2008 Mazda 3 Hatchback, 1984 RX7 GSL-SE
My car has misfired one too many times due to bad coil packs or plugs over the years and the cat is clogged up, causing back-pressure. I don't know much about cats and have a couple questions.

1. Does the MSP have the same cats as a standard protege? Do the cats on rockauto look like they're compatible (sometimes they're wrong with the MSP...)
http://www.rockauto.com/en/catalog/...rged,1416822,exhaust,catalytic+converter,5808
Specifically, I'm looking at the Walker bolt-on cat which would be $126 after a rebate.

2. Is there a different cat I could use that might improve my performance without spending much more? The car is 100% stock now but I wouldn't say no to a little more power when there's an opportunity.
 
We've got a pre-cat and cat. I took mine off years ago but still have it hanging in my shed. Unless you have an emissions inspection, why not just go catless? Have an exhaust shop fab up some piping, add a non fouler and no more emissions bs backpressure.
 
Thanks. Good to know Rockauto's are wrong.

I don't want to go catless because I might move back to an emissions state in the next few years, and because my other car is an rx7 and my wife doesn't want both my cars to "make the house smell like cancer"... so yeah, I need a cat. Has anyone had success just buying the cat itself and having an exhaust shop fabricate the pipe for it? If so, can anyone recommend a cat that would work?
 
Thanks. Good to know Rockauto's are wrong.

I don't want to go catless because I might move back to an emissions state in the next few years, and because my other car is an rx7 and my wife doesn't want both my cars to "make the house smell like cancer"... so yeah, I need a cat. Has anyone had success just buying the cat itself and having an exhaust shop fabricate the pipe for it? If so, can anyone recommend a cat that would work?
Austin, I'd recommend having the failed converter(s) cut from the exhaust and replacements welded into place.
 
Thanks Chris. Do you have a specific cat you'd recommend that I can order and bring to the shop or should I just let them handle it all?
 
Thanks. One last question then. Will switching to a high-flow cat alter how the car runs or cause a CEL on a stock car?
 
Unlikely there would be any noticeable difference and, as long as the correct type and size converter is installed for the application, you'll have no drivability concerns. And Kar Kare keeps converters on hand. I've always let them use their own stocking converters, but I have brought them my own resonators.
 
BTW, did you sell your spicy?
 
Yep! Sold it a few months ago to a guy in Lenoir City for a total profit of $84. I'm shocked I didn't loose money on it, and I'm glad it's back on the road
 
Shop quoted me $400 to replace them. That's higher than I expected. Is it reasonable?
 
That sounds high to me, you could order some high flow cats online and have them installed. Personally I would just delete them or find a used midpipe for ~$100.
 
I'd assuming you took it to KK per my recommendation.
They charge $200 installed for most converters for walk-ins. They do them for me for $150 installed. I wouldn't have figured Mark would have double-tapped you on labor which is what it looks like he did.

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I wound up getting it swapped to single new cat. Got the whole midpipe replaced for $225
 
I had to do that after my cat broke in half. With the single cat pipe I had to weld a O2 bung in right behind the cat so the sensor would not throw a CEL. I also had to extend the wire harness for the sensor. It's pretty far back under there now. But it all works fine now.
 
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