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2003 chevy trailblazer_ls
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104 Posts
Discussion Starter #1
Hello, I was pondering whether to remove my catalytic converter or not, to increase the sound, one mechanic said it will get louder, another said you won't notice much difference unless the cat is plugged. i have an 03 tb ls 4.2l i6, with almost 140000km on it. What are your guy's thoughts?
 

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Northwest Chapter
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11,824 Posts
Not worth it, have to deal with the check engine light. Maybe worth 2-5hp and yes it will be louder. Dont know what your emissions situation is, but it wont pass without a cat if they put a sniffer in the exhaust.

If its clogged and your mileage is shot, just get a generic replacement one and have a shop weld it in.
 

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2003 chevy trailblazer_ls
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104 Posts
Discussion Starter #3
ok thanks

what about a performance cat? the sensor will be fine, and what about the noise level? have you had experience with performance cats?
 

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Northwest Chapter
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Performance cats usually just flow more (not necessary on the I6 as N/A you cant outflow the cat without a ported head and cams), not sure about noise. PM BUC NASTY and see what he has to say about his, think he's got a Magnaflow performance cat on his 02.

Sensor should be fine with any cat, so long as its not gutted :laugh:. But if yours is still fine, you'll just be throwing $$ at it with an aftermarket cat for very little/no performance (or for some reason you're after noise) increase.

Your call, but I think Ive said it before a few times on TV.com, buy a tune first then CAI, then exhaust if you want sound and performance. If its too quiet, then straight pipe it. No way you could pay me to sit in a straight-piped I6, had enough of that with just a 3" Magnaflow catback on my 02.
 

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2006 chevy
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1,659 Posts
It won't be legal, but some Cobalt guys use a spark plug spacer to pull the rear O2 sensor out of the exhaust stream to fool the PCM after doing a cat delete. Or IIRC PCM4less can tune for the cat delete.
 

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Northwest Chapter
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It won't be legal, but some Cobalt guys use a spark plug spacer to pull the rear O2 sensor out of the exhaust stream to fool the PCM after doing a cat delete. Or IIRC PCM4less can tune for the cat delete.
True, some I6s guys have done that as well. Seems to work about 75% of the time with 1, some have to run 2 together.

P4L (anyone with HPTuners/EFILive/TunerCats) can turn off the rear O2 codes, I forget what it does to the Closed Loop fueling mode though.
 

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2002 chevy
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2,582 Posts
Performance cats usually just flow more (not necessary on the I6 as N/A you cant outflow the cat without a ported head and cams), not sure about noise. PM BUC NASTY and see what he has to say about his, think he's got a Magnaflow performance cat on his 02.
The Magnaflow "direct fit" performance cat has the same performance as the OEM Cat except the Magnaflow is much cheaper than OEM. There was no change is on the noise level. Its as if installing an OEM cat.

Sensor should be fine with any cat, so long as its not gutted :laugh:. But if yours is still fine, you'll just be throwing $$ at it with an aftermarket cat for very little/no performance (or for some reason you're after noise) increase.
The Magnaflow direct fit cat accepts the sensor. So, by installing the sensor will pose no problem with engine codes lighting up nor losing performance.
 
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