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Old 05-13-2005, 12:42 PM
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Default Gutted cats

I know this is a common topic, I've been reading stuff on here for a long time but just signed up today, but I was wondering about performance changes from gutting cats. All that I have seen just talked about how good it sounds. Does it hurt low end from a lack of backpressure?
Old 05-13-2005, 12:53 PM
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there is alot of things that can factor in to this. basically on a stock N/A vehicle, most dont see more than maybe 5 hp/tq out of this. i didnt feel really anything when i did mine. it can depend on the rest of your exhaust setup too though. its mainly to change the exhaust note/sound of your vehicle. i didnt feel any low end loss when i did mine.
Old 05-13-2005, 02:43 PM
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I totally removed the cats on mine when I installed my headers. 2 1/2 inch pipe from the headers to the x-pipe, then 2 1/4 from the x-pipe to the muffler. A friend of mine said it was a good setup because I could get good back-pressure. My truck has been a little louder since the cats were removed, but I really like the sound, there's no restrictions in the exhaust at all, and it's got more room to breathe now. As far as performance, I haven't noticed a drastic change...I haven't tested it at the track ...It's all up to you...

Old 05-13-2005, 04:52 PM
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Originally Posted by Black_Silverado_5.3
I totally removed the cats on mine when I installed my headers. 2 1/2 inch pipe from the headers to the x-pipe, then 2 1/4 from the x-pipe to the muffler. A friend of mine said it was a good setup because I could get good back-pressure. My truck has been a little louder since the cats were removed, but I really like the sound, there's no restrictions in the exhaust at all, and it's got more room to breathe now. As far as performance, I haven't noticed a drastic change...I haven't tested it at the track ...It's all up to you...

If you remove the cats, is it triggering the Check Engine Light???
Old 05-13-2005, 05:00 PM
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Originally Posted by GenIII53
If you remove the cats, is it triggering the Check Engine Light???
Yes, it will. But's nothing a custom tune can't fix.
Old 05-13-2005, 05:07 PM
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Originally Posted by Tiburon
Yes, it will. But's nothing a custom tune can't fix.
Roger that, thanks.
Old 05-13-2005, 05:20 PM
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if you have tuning software delete the rear 02's and cut them out also, they are useless then no se light. I noticed an enormous seat of the pants difference throughout the rpm range and also throttle response was better feels like a good 20 rwhp.
regardless of whether you have extensive mods or not the cats are very restrictive and free up alot of power.
Old 05-13-2005, 07:00 PM
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Originally Posted by 02sierraz71_5.3
if you have tuning software delete the rear 02's and cut them out also, they are useless then no se light. I noticed an enormous seat of the pants difference throughout the rpm range and also throttle response was better feels like a good 20 rwhp.
regardless of whether you have extensive mods or not the cats are very restrictive and free up alot of power.
ive heard both ways myself too. ive heard by taking them out, i will get an enormous amount of gains, and ive heard its a waste of time barely worth 5 hp. many people claim the stock cats flow very well i dont know. i am just saying i didnt notice any difference at all when i did mine. only a much better sound, which in my book was worth it.
Old 05-13-2005, 07:15 PM
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My friend CAMMIN03 cut his out on his 03 and got just over 20rwhp and i think like 12rwtq from removing them. However, they were clogged for whatever reason, but you could def. feel the difference in his case.
Old 05-13-2005, 07:20 PM
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Actually beeftip it was 22rwhp.... 27ftlbs


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