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Discussion Starter #1
I'm looking to install new headers on my GenCoupe, but I'm forced to take emissions tests every two years, so I'm not interested in putting the stock ones back on before each test. Are there companies that make downpipes with cats so I can leave the catless headers in place? And would it be possible to run the car on just the secondary cats to pass emissions? Vice versa, if the car is tested with the stock headers, but with test pipes installed, what are the odds of me passing emissions?
 

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First question, no.

Second question, depends on where you live and how much you want to spend. If you live in a state where they do not check if the secondary 02 sensors are turned on you can get a canned tune to turn them off, keep the secondary cats installed and you should be fine. If you live in state that does check the sensor state you need to have the secondary sensors relocated after the secondary cats and get custom tuned to run that way.

Third question, unless they do a visual inspection under the car and spot them test pipes alone will not cause you to fail.
 

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Discussion Starter #3
Connecticut emissions tests require both OBD2 software inspection and visual inspection. I talked to Jay over at SFR and he's fabricated a set of cats onto some downpipes for a BK1 GenCoupe. He said it may be possible to do the same on a BK2, so hopefully I can get that process started up.
 

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Just because a state hooks up to your OBD2 doesn't mean they check readiness of the secondary sensors but I believe Connecticut does, Texas where I am does not, anyone considering this needs to do the research for their home state. IMO the visual inspection is more likely to catch the missing secondary cats than it is the headers in which case completely ditching the primaries and tuning for moving the secondary sensors is still the way to go but it's up to you.
 

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Discussion Starter #5
Just because a state hooks up to your OBD2 doesn't mean they check readiness of the secondary sensors but I believe Connecticut does, Texas where I am does not, anyone considering this needs to do the research for their home state. IMO the visual inspection is more likely to catch the missing secondary cats than it is the headers in which case completely ditching the primaries and tuning for moving the secondary sensors is still the way to go but it's up to you.
Would the car have to be tuned to accept the secondaries as the only cats, or are they good enough alone to avoid throwing codes during inspection? The other 99% of the time I'll be running a tune that turns the sensors off when the test pipes go back in. Obviously it would be a pain in the ass to relocate the O2 sensors and have new bungs fabricated on the exhaust, but it's far easier than switching the headers every two years out.
 

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In my time here on the forum over the years the owners who have opted to, or needed to keep both sets of sensors working have had little or no luck without custom tuning, eventually you'll get a CEL even if properly relocated with defoulers, and sometimes the car won't run right depending on other mods or prior tuning. It's not that big a deal to relocate the sensors, any shop that can do exhaust and electrical work can do it.
 

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So I have a 2013 2.0T so not the same, but I have been successfully running a CP-E downpipe w/ highflow cat for months now. I live in NC and they hook up the OBDII sensor and look for a ready state and no CEL. I just passed my annual inspection without any questions. I'm on a 1.5 canned tune from SFR.

You can always search out "friendly" inspection stations.
 

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Discussion Starter #8
Since it's looking more and more like changing the location of the cats is going to be difficult and not very cost-effective, what's the best way to switch the headers? Tips and tricks for getting them out and putting new ones in?
 

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Since it's looking more and more like changing the location of the cats is going to be difficult and not very cost-effective, what's the best way to switch the headers? Tips and tricks for getting them out and putting new ones in?
Most people I know who go through this say it's best to unbolt the engine/trans mounts and jack the engine up a bit. Gives you a tiny bit of side to side wiggle room too, but you must be very careful not to smash or yank on anything. Most who raise the engine do so from the oil pan using some sort of weight distribution hack; chunk of 2x8 or something. I would advise an engine hoist or crane to avoid potential heartache and it might be worth your time to pull the front clip for extra leeway, though that would effectively double the swap time.
 
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