Active Autowerke | MKV Supra EPA Approved Catted Downpipe

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Reppunkamui

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There is only one cat

Kracer guy here says its two
Thanks for providing photos and confirming.

I was staring at the OEM exhaust diagrams and wondering how they fit a cat in front of the first O2 sensor.
 

MA617M

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There is only one cat

Kracer guy here says its two

B87DEAB4-94B4-4E9A-8A89-689F24E591D1.jpeg


9ED348F1-D93D-4F23-B067-227E040441DD.jpeg


5B5A703B-9563-4D92-B41E-2372E65DB815.jpeg
Thanks mate that's awesome. I knew there was one, I was wondering where old mate got confused haha. Great pics! I might pm you about some measurements from the OE dump pipe if that's ok?
 

a90moe

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Thanks mate that's awesome. I knew there was one, I was wondering where old mate got confused haha. Great pics! I might pm you about some measurements from the OE dump pipe if that's ok?
Sure man anytime :thumbsup:
 

Kracer

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Hi guys. Yes, there are two cats in the factory downpipe.

The primary cat is circled in blue in the pic below, and the secondary cat is circled in red.

There is an air gap between them, and the second O2 sensor is at the yellow arrow. That sensor monitors the primary cat. The main O2 sensor is at the green arrow.

Capture_1.JPG
 

Reppunkamui

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Why would there be a cat with no sensor after it?
 

Reppunkamui

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I don't know, but that's not something unique to this car. Every gasoline car for the last 10 years or so is set up the same way for the US market.
Ok, I'll take your word on it. I only look at inline 6s (may be different for other engine setups) and its usually one right after the manifold to the cat and one after, sometimes a 3rd in between 2 cats. This sort of setup makes sense to me for modifying A/F ratios to reduce emissions.
 

a90moe

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Hi guys. Yes, there are two cats in the factory downpipe.

The primary cat is circled in blue in the pic below, and the secondary cat is circled in red.

There is an air gap between them, and the second O2 sensor is at the yellow arrow. That sensor monitors the primary cat. The main O2 sensor is at the green arrow.

Capture_1.JPG
So if I take a peep through that second sensor hole there should be a gap of some sorts or break between the two cats?

Any evidence to back this up?

F8X for instance had the secondary cats at the mid pipe

I don't want to dissect my DP for science :D
 

Kracer

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Yep, look through the hole, there is a gap there.

I didn't mean to say that all secondary cats sit this close to the primary one, some are spaced further away because of space limitations in the exhaust path. Vdubs are close together like this one.

But a secondary cat isn't monitored by an O2 sensor. That's why you can delete them and the car won't notice.
 

JasonO

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So if I take a peep through that second sensor hole there should be a gap of some sorts or break between the two cats?

Any evidence to back this up?

F8X for instance had the secondary cats at the mid pipe

I don't want to dissect my DP for science :D
If you look at the pics posted above by a90moe, you can see the cat he is referring to after the corrugated section in the picture looking up the downpipe.
 

a90moe

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367F2767-E8AE-485B-80C5-3035E3433CC3.jpeg


Looks like two cats with a space in between as stated by @Kracer

Makes sense now as to why the OE DP is this big to start with :D

This is making me love my AA DP even more ;)
 

digicidal

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Yeah, I'm thinking if your smog guy is that crazy about digging through the whole engine bay or putting it on a lift to be able to tell the difference... then you need a different smog guy. Preferably one that will ask why you didn't just go test pipes to the street.:p

That's probably because, while I do lament the state of the environment, at the same time - I strongly think the EPA can blow me. :hide:
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