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Discussion Starter #1
well, i'm putting my exhaust on next tuesday, and i'm building my own, i found a can that will set between my rear suspension and my bumper, with just a enough room and i've heard it on another focus around here and it sounds great, but i'm also wanting to replace my cat with a high flow, and i'm wanting to see if any of you have replaced your cat with a high flow, and what would be the best one to go with, any help would be great!
 

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if you live in a green state and are doing the cat to be legal then you are out of luck, there are no OBD-II aftermarket cats that are actually legal to use yet at least in CA, it has to be factory unless you are beyond 100k miles I believe

If you just need to pass a sniff test in another state you can still do that without the second cat
 

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I hate to break it to you, but there's no such thing as a "high-flow, CARB-legal catalytic converter". CARB-legal cats must be OEM-style, which means a fairly dense catalyst grid. IIRC, you can't replace them anyway unless the original is damaged, and you have to prove that the old one was damaged every time the car is inspected.
 

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just get the long tube header....... totally catless and swap in the OEM when emissions comes around..... you'll be much happer and stright pipes cost less that catalyic converters !
 

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just get the long tube header...
What? This is Duratec Tuning. They don't make "long tube headers".
 

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The race header is the long tube. "race header" just sounds like its faster.

What muffler are you going to install?
 

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The race header is the long tube. "race header" just sounds like its faster.
Well, the race/long tube header doesn't remove bot cats, which he said it did. I thought he was talking about Zetecs, which have "short" and "long" headers, and in which the long tube removes the only cat.
 

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Thats true, but why would you put a header on and leave the second cat?(if your putting the header on emissions arn't your top priorities so don't give me that.)
 

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Thats true, but why would you put a header on and leave the second cat?(if your putting the header on emissions arn't your top priorities so don't give me that.)
Why not? A Duratec with one high-flow cat is still a very clean vehicle. Emissions don't have to be your top priority for you to still care. Are you saying it's impossible to hold an opinion in between "fur is murder" and "pave the rain forest"?
 

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Thats true, but why would you put a header on and leave the second cat?(if your putting the header on emissions arn't your top priorities so don't give me that.)
I'm doing it to keep noise levels down.
 

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Discussion Starter #14
i don't live in ca, i live in arkansas, and we don't have emission tests where i'm at, so i can do whatever is better. and i'm putting a lawson muffler on the car, 12" total length and it fits almost perfect, i went and looked at the muffler yesterday

also, would it really be that much louder if i removed the cats, because i want loud as possible, but i don't want too much noise
 

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Discussion Starter #16
what i mean by too much noise is the popping that exhaust can sometimes have like there is too much backpressure
 

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Generally, that popping sound only shows up when you release the throttle, and it's not usually caused by backpressure. In fact, the less backpressure the system has, the more it usually pops. Rally cars have some of the most freeflowing exhausts around, and they pop every time the driver lifts.
 

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Im not saying you can't be in the middle. I just think if your going through all that(header and exhaust), go all the way. The header is going to reduce the life of the cat, put flanges in and your set for smog testing.
Install a resonator in the middle of the tunnel, that will help with the increase in noise.
 

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The header is going to reduce the life of the cat,
How so? High-flow cats are designed to work as the only cat in a system, and the reputable brands are warranteed for 5 years or 50,000 miles. That's only half as long as the stock parts are warranteed for.
 
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