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SO i got the ISR street performace cat back with the 3"downpipe i have to have a cat due to where i live i was lloking to get some high flow cats to replace the 2 on the vehicle or maybe just delete the second from what ive seen you can still pass emissions with the main cat installed but i cant for the life of me find a high flow cat to replace the oem one any suggestions ?
 

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Not sure what your state/country inspections require, but most places you can pass without a secondary cat. The O2 sensors are before and after your primary cat, so as long as the primary is doing its job it comes back "clean". If they are using the OBDII port the O2 sensor should pass. Likewise if they use a sniffer one cat may still pass. That said I've heard some places physically inspect and will fail you if they don't see all factory cats.
 
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Not sure what your state/country inspections require, but most places you can pass without a secondary cat. The O2 sensors are before and after your primary cat, so as long as the primary is doing its job it comes back "clean". If they are using the OBDII port the O2 sensor should pass. Likewise if they use a sniffer one cat may still pass. That said I've heard some places physically inspect and will fail you if they don't see all factory cats.
I appreciate the reply but do you know of any high flow cat that would replace the primary ?
 

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What is better for perfomance? high flow cat or no cats? i heard high flow cats give more pops but i think its the opposite. Also, when going catless, would i have to change any 02 sensors?
 

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I mean, no cats are optimal flow, least restrictions. So for performance no cats will always be the best. A high flow is still restrictive, just designed better than stock ones. Cats require some expensive precious metals to function, they aren't cheap but they do a lot of work stopping pollutants before the exit the car. I wish more manufacturers focused on this part, but it is generally not worth it for them.

I am not aware of many high-flow cat options for our car other than some custom stuff and the CP-E downpipe I used to run on my BK2. Custom because most O2 housing replacements are just for cat-deletes and not keeping your cat.

The CP-E downpipe for the stock BK2 turbo setup has a primary cat-option for an extra $150. Mine is for sale if interested send me a DM. Pretty sure it was less than 10K miles on it (5-7K seems accurate). Never had a check engine light or O2 CEL. NOTE this only works with the BK2 stock turbo and will not work with after market turbos. This is the only reason I no longer use it. When I went to a different turbo setup I had to get another downpipe.
- CP-E Hyundai Genesis Coupe 2013-14 2.0T QKspl™ 3″ SS Genesis Turbo Downpipe
 
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