AP Exhaust Catalytic Converters?

Joined
May 28, 2019
Messages
232
Location
CA
Hi

I am in California and need to replace the Catalytic Converter in my car.

On the California aftermarket database there is a listing for an AP Exhaust Cat as well as a Magnaflow.

I have never heard of AP Exhaust and wanted to know if others have used thier Cats and found them to be a quality part.

Thanks
 
Hi

I am in California and need to replace the Catalytic Converter in my car.

On the California aftermarket database there is a listing for an AP Exhaust Cat as well as a Magnaflow.

I have never heard of AP Exhaust and wanted to know if others have used their Cats and found them to be a quality part.

Thanks

No direct experience here. I'm sure you know that aftermarket catalytic converters often fall short of OEM quality and performance, even the very best ones. In restrictive locations, it is a safer bet to use the OEM part, trying to find the best price of course.

Sure, aftermarket units could be built to better than OEM standards. Good luck figuring out which ones those might be, if any.

I've used plenty of aftermarket cats, especially in performance applications. Not once have I been able to match OEM tailpipe numbers. Some failed horribly, some passed by the thinnest of margins. Guessing the OEM does not want warranty or government trouble in the world of tailpipe emissions, so they tightly control the catalytic converter quality.

While this won't apply to today's world, in a distant past life I worked as a dyno/engineering tech testing an emission compliant roller camshaft for a Ford turbocharged engine. We got the product correct and the specs were used in production. I did get to observe the dyno runs, the emissions data, and of course swap out engines and camshafts for about 150 compliance dyno runs.


A few years back, I had a 2004 Honda S2000, with the Inline-Pro stage 1 turbo kit and aftermarket metal matrix cat. Since FL does not have testing, I don't know what the numbers were, but the car ended up in FL because it would not pass testing elsewhere. It mattered not one bit that the engine was 100% bone stock. That car would make eyes water!

MaKGi0o.jpg
 
No direct experience here. I'm sure you know that aftermarket catalytic converters often fall short of OEM quality and performance, even the very best ones. In restrictive locations, it is a safer bet to use the OEM part, trying to find the best price of course.

Sure, aftermarket units could be built to better than OEM standards. Good luck figuring out which ones those might be, if any.

I've used plenty of aftermarket cats, especially in performance applications. Not once have I been able to match OEM tailpipe numbers. Some failed horribly, some passed by the thinnest of margins. Guessing the OEM does not want warranty or government trouble in the world of tailpipe emissions, so they tightly control the catalytic converter quality.

While this won't apply to today's world, in a distant past life I worked as a dyno/engineering tech testing an emission compliant roller camshaft for a Ford turbocharged engine. We got the product correct and the specs were used in production. I did get to observe the dyno runs, the emissions data, and of course swap out engines and camshafts for about 150 compliance dyno runs.


A few years back, I had a 2004 Honda S2000, with the Inline-Pro stage 1 turbo kit and aftermarket metal matrix cat. Since FL does not have testing, I don't know what the numbers were, but the car ended up in FL because it would not pass testing elsewhere. It mattered not one bit that the engine was 100% bone stock. That car would make eyes water!

MaKGi0o.jpg

nice oil filter location on that S2000 :D
 
Hi

I am in California and need to replace the Catalytic Converter in my car.

On the California aftermarket database there is a listing for an AP Exhaust Cat as well as a Magnaflow.

I have never heard of AP Exhaust and wanted to know if others have used thier Cats and found them to be a quality part.

Thanks
I'm assuming that the AP cat is CARB approved? If there isn't much difference on price oem is the way to go.
 
No direct experience here. I'm sure you know that aftermarket catalytic converters often fall short of OEM quality and performance, even the very best ones. In restrictive locations, it is a safer bet to use the OEM part, trying to find the best price of course.

Sure, aftermarket units could be built to better than OEM standards. Good luck figuring out which ones those might be, if any.

I've used plenty of aftermarket cats, especially in performance applications. Not once have I been able to match OEM tailpipe numbers. Some failed horribly, some passed by the thinnest of margins. Guessing the OEM does not want warranty or government trouble in the world of tailpipe emissions, so they tightly control the catalytic converter quality.
This was my experience as well. I used a carb certified company to rebuild the catalyst for a 1990s OBD2 Ferrari I used to own. It worked for about 7 months (on a car only driven on occasional weekends) before it started giving the dreaded "low catalyst efficiency" codes. I sent it back, they recored it, and it failed again in four or five months. I ended up shopping around and found a brand new factory catalyst on eBay, installed it and never had any further issues.

There is a pretty big aftermarket industry for catalysts for exotic cars, as the factory ones are so expensive. According to technicians that are active on the forums, most all of them eventually start giving "low catalyst efficiency" codes. The Bosch Motronic is very sensitive to the readings on modern cars and just works best with OEM catalysts. Its not a Ferrari thing, just modern cars are getting really tight on the specifications.

I saw threads of people trying Magnaflow and other options, they work for a while...none worked longer term. Many people ended up cheating and using O2 sensor "extenders" and what not to pull the sensor out of the exhaust flow and prevent the codes.

The AP brand might work fine....wishing you luck if you try, but I would just shop around for the best deal on an OEM. One and done.
 
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OEM CARB catalytic converter prices are sometimes out of the world post 2020. My 98 BMW 328i was over $4k for the cat assembly. Car was worth about $4k. I got it to pass and sold it, I did disclose it to the seller. He owned a BMW shop and didn't care.
 
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