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Discussion Starter #1
Inspired by Buckket's exhaust build, I gave it a go. Used a Flowmaster high flow cat, the cutest little muffler I could find on Amazon, and 2" SS piping. This was the 3rd and hopefully final(ish) rendition. Still have some in-car drone to work out, but it isn't as bad as with the 2.25" piping. The setup is pretty damn loud, but not terrible.
63714
 

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Welp, ended up re-installing the stock cat. I got annoyed with the sound and kept getting a check engine light for cat efficiency. Turns out the cat I purchased was for a pre-OBD-II system, That'll do it every time. For the mean time, I just cored out the post-downstream O2 sensor cat matrix to get my "turbo sounds" back that were muffled. Still pretty quiet, get to hear the spool, and hopefully no cat codes.
 

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This got rid of the cel on my 450 with a 200cpsi cat :)

The 450 was on the EURO 4 emission standard however.

I haven't installed a high flow cat on my 453 but it's EURO 6 2014+ so I haven't had a chance to try this 'cat inside the bung' on a 453 sensor.

 

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This got rid of the cel on my 450 with a 200cpsi cat :)

The 450 was on the EURO 4 emission standard however.

I haven't installed a high flow cat on my 453 but it's EURO 6 2014+ so I haven't had a chance to try this 'cat inside the bung' on a 453 sensor.

Mailman, tried one of those as well. This is the first car I have had that the extension didn't fix.
 

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Mailman, tried one of those as well. This is the first car I have had that the extension didn't fix.
The problem with the extension is you get a heater circuit fault you basically need to insert a sealed pipe into your exhaust so the sensor sits inside the exhaust flow but will only get the exhaust heat and not the actual gas that way you don't get a efficiency fault or heater circuit fault
 

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Until I can find a compact 400 cell OBDII compatible cat, this will have to do. More sound and no codes will be good enough for a while.

If I feel froggy I'll try what Bucket suggested and seal the O2 sensor.
 

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Until I can find a compact 400 cell OBDII compatible cat, this will have to do. More sound and no codes will be good enough for a while.

If I feel froggy I'll try what Bucket suggested and seal the O2 sensor.
Think about it as a reverse extension but inwards instead of outwards. Remember the secondary O2 sensor only checks catalytic converter efficiency so by plugging the ports the sensor will get up to temp but not read the fact that the cat is not present. The system wants to see that difference between the Primary and secondary sensor. I am hopefully going to be trying a new exhaust system in the next few months
 
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