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I had just purchased a new shorty header and plan on getting the Megan High Flow down pipe and cat, with a cat back exhaust. I was wondering if anyone else had a high flow cat and still needed to use an O2 sim sensor or if it isnt needed as long as it has a cat.
I know of people putting in new exhaust set ups with no cat and needed to use this just wondering if so in my case.

 
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CEL will come up with Megen testpipe.

 
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Thanks it will come up so I guess I will need to order one
Appreciate it
SIM SENS IT IS