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As we all know, our stock headers contain a cat necessary for state legal emission inspection. I was doing some thinking about replacing the stocker with a less restrictive, CEL throwing, growling monster. I have an electric exhaust cutout before the 2nd cat, so restriction after the cutout isn't really an issue for me, I already have a high-flow cat, large muffler, resonator, and silencer on it.

Could you possibly put two cats on the exhaust piping itself (even though, yes, i know this will strangle the flow, and make any aftermarket exhaust system pointless) in order to remain emissions legal. (Im lazy and I don't want to have to switch headers on and off every year)

I plan on using the cutout like a really short test pipe with the race headers. It would be unrestricted with the flange open, but emissions legal with it closed.
+ The cutout can be opened to varying degrees for different power amts., backpressure, and sounds/smell level :?


Is the two cats thing possible?
 

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im lost with what you're wanting to do.

why do you need to add an extra cat? that's poinless. just delete the 2nd one. you can pass emissions without it.
 

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you can pass it? I didn't know that you could get by with only one cat.. So...you can pass emissions with a race header?
 

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i get what u r trying to say. that makes sense to me, but i wouldnt worry about it. it takes a total of 20 minutes to take out an aftermarket header and after u've chopped the stock exhaust manifold to get it out it won't take long at all to get beack it. just get a vibrant header and put the stock one back in for inspection. ur not supposed to get a cel with the vibrant headers if u put it in right with the O2 bung after the second cat... i think i got mine right now because i dont have a cel... mean performance gains by the way...
 

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[quote author=p1r0 link=topic=68687.msg1187743#msg1187743 date=1170697203]
you can pass it? I didn't know that you could get by with only one cat.. So...you can pass emissions with a race header?
[/quote]

96 and newer vehicles don't do the sniff test. all they do is hook ur car up to a scanner and check for codes. if you aren't throwing any codes, you will pass.

there are some instances where your county still requires a sniff test. those are few and far between.

read more here: http://www.mazda3forums.com/index.php?topic=67349.0
 

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[quote author=the415 link=topic=68687.msg1187887#msg1187887 date=1170702981]
[quote author=p1r0 link=topic=68687.msg1187743#msg1187743 date=1170697203]
you can pass it? I didn't know that you could get by with only one cat.. So...you can pass emissions with a race header?
[/quote]

96 and newer vehicles don't do the sniff test. all they do is hook ur car up to a scanner and check for codes. if you aren't throwing any codes, you will pass.

there are some instances where your county still requires a sniff test. those are few and far between.

read more here: http://www.mazda3forums.com/index.php?topic=67349.0
[/quote]

Check your local DMV site to see if your county does the sniffer. Mine does. :x
 
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