real experience : gutted cats
Thread Starter
Pro
Joined: Dec 2017
Posts: 589
Likes: 53
From: Plymouth Minnesota
real experience : gutted cats
I am looking for real experience from you that have operated with gutted cats.
* * Please do not respond if you have not personally done this. * *
I am wondering about changes in exhaust sound with a gutted cat?
I am wondering about exhaust smell with a gutted cat?
Did disabling the 2nd oxygen sensor change anything?
Thanks for letting me know your experience
* * Please do not respond if you have not personally done this. * *
I am wondering about changes in exhaust sound with a gutted cat?
I am wondering about exhaust smell with a gutted cat?
Did disabling the 2nd oxygen sensor change anything?
Thanks for letting me know your experience
Race Director
Joined: Dec 2013
Posts: 12,500
Likes: 3,625
On a LS motor, you loose about 4HP total with high flow cats, then no cats instead.
On gutted OEM cats, you may gain a touch of HP, but still going to have a lose at least 4hp or more, due to the bottle next section at the back of the gutted cat.
Worse, with out cats on the car, the cabin is going to stink of unburnt fuel every stop light is the wind in not in your favor. If the wind is in your favor, then car behind you cabin is going to stink of un-burnt fuel instead.
As for the rear 02 sensors, only used to see the performance of of the cats, so if removed and turned off. not a problem. If left on with either high flow cats, or gutted cats, will be throwing codes.
So bottom line, you can replace the OEM cats with High flow cats on the cheap, and the best of both worlds. If the high flow cats are installed in the OEM locations, then you can leave the rear O2 sensors in play as well. Its when the high flow cats are moved down stream on the OEM locations with long tube headers, then they become slightly less effective (farther from the heat source), and why the rear O2 sensor are deleted in these cases instead.
On gutted OEM cats, you may gain a touch of HP, but still going to have a lose at least 4hp or more, due to the bottle next section at the back of the gutted cat.
Worse, with out cats on the car, the cabin is going to stink of unburnt fuel every stop light is the wind in not in your favor. If the wind is in your favor, then car behind you cabin is going to stink of un-burnt fuel instead.
As for the rear 02 sensors, only used to see the performance of of the cats, so if removed and turned off. not a problem. If left on with either high flow cats, or gutted cats, will be throwing codes.
So bottom line, you can replace the OEM cats with High flow cats on the cheap, and the best of both worlds. If the high flow cats are installed in the OEM locations, then you can leave the rear O2 sensors in play as well. Its when the high flow cats are moved down stream on the OEM locations with long tube headers, then they become slightly less effective (farther from the heat source), and why the rear O2 sensor are deleted in these cases instead.
Last edited by Dano523; Mar 31, 2020 at 03:11 AM.
Advanced
Joined: May 2003
Posts: 76
Likes: 8
From: Wetumpka AL
I gutted mine years ago after installing supercharger setup and disabiling downflow O2 sensors. Yes there is a higher exhaust fuel smell especially stopped with wind behind you. I gutted mine because they were deteriorating due to my aggressive setup. The exhaust does get louder, but not excessive. I don't miss them at all and can deal with some smell. I also didn't have go through the expense of high flow installation and kept the housings for inspections. No tailpipe sniff in my area.
Race Director
Joined: Dec 2013
Posts: 12,500
Likes: 3,625
I gutted mine years ago after installing supercharger setup and disabiling downflow O2 sensors. Yes there is a higher exhaust fuel smell especially stopped with wind behind you. I gutted mine because they were deteriorating due to my aggressive setup. The exhaust does get louder, but not excessive. I don't miss them at all and can deal with some smell. I also didn't have go through the expense of high flow installation and kept the housings for inspections. No tailpipe sniff in my area.
Don't be that guy!!!!!
When my grand parents where still alive, greatest pleasure for my grand mother was to just have my grandfather take her for a drive to just get out of the house and see town changes (small town at that,, so most of the drive was just slow in town traffic driving). Now someone like you comes along, they end up behind you, and what was going to be a pleasurable afternoon ride, just ends up with them being gassed out instead.
So again, your only going to lose 4Hp with High flow cats, High flow cats are cheap to install in the grand scheme of owning a vet to begin with, do it for the other people around you that you're going to share the road.
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Thread Starter
Pro
Joined: Dec 2017
Posts: 589
Likes: 53
From: Plymouth Minnesota
real experience : gutted cats
To those of you that cannot resist giving your judgements, opinions, and personal playbooks :KEEP IT TO YOURSELF !
The request clearly stated: personal experience only.
Nowhere did I state or imply doing a cat delete is on my agenda.
This request is for factual experiences to support a discussion myself and some local owners talked about last weekend.
TO REPEAT ! ! ! Please keep anything other than actual experience to youself.
The request clearly stated: personal experience only.
Nowhere did I state or imply doing a cat delete is on my agenda.
This request is for factual experiences to support a discussion myself and some local owners talked about last weekend.
TO REPEAT ! ! ! Please keep anything other than actual experience to youself.
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gutted mine because they failed and dropped into the pipe downstream.....BTW these were PFADT headers....the original ones before they went out of business and were bought
Last edited by pewter99; Mar 31, 2020 at 09:28 PM.
Melting Slicks
Joined: Apr 2008
Posts: 3,242
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From: Fauquier, VA
Team Owner
Joined: Dec 1999
Posts: 174,312
Likes: 1,216
From: Here
Pilot of Beer Force 1
Tampa Regional Coordinator
CI 4-5-6-7-8 Veteran
Organizer St. Jude Fundraiser
I believe in the Beer Fairy
you are telling me....never made any sound, exhaust note was unchanged and the car ran fine otherwise...discovered because I had a lifter fail and during the tear down Joe at Powertech Performance noticed I had an exhaust leak at the header flange so we sent them out to be machined, when they went to hang everything up he noticed a rattle and thats what we found. I have another pic where you can see where the one pipe got hot (discoloration) and we are thinking that perhaps that is what caused the leak at the flange due to some excessive back pressure although we don't really know.*I should say they are all jacked up because of what he had to do to get them out of the pipes*
Last edited by pewter99; Mar 31, 2020 at 10:39 PM.
Drifting
Joined: Jul 2006
Posts: 1,786
Likes: 93
From: Charlotte N.C.
Gutted mine because turbos ruined them every few years. Bit louder with my Corsa’s but not real bad. Hate the smell! Had to richen up my MAF curve due to running more lean after so on a turbo car at least it significantly improved breathing. Not sure what it was worth in terms of HP as I really don’t need more and did not do it for that reason.
Pro
Joined: Oct 2009
Posts: 679
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From: Durham North Carolina
Gutted Cats
I've ran gutted cats on 4 vehicles. 1989 formula, 1990 trans am gta, 1999 trans am and my 08 Vette. All automatic transmissions with headers. Drone and rasp was progressively louder with each vehicle listed. All had 3 inch main or intermediate pipes too. The exhaust smell was my main reason for swapping. I couldn't deal with smelling like I stood behind and aircraft during an engine run. It sounds ridiculously mean, but it does get old when you can't have a conversation or run your AC. Forget about taking the top out. I put the cats on and loving life without setting off alarms and rattling my interior loose
Team Owner
Joined: Nov 2006
Posts: 21,136
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From: Long Island New York
Gutted my cats in mine for the same reason as pewter. Two sets of LG cats melted and clogged the exhaust. Once chuck jammed my NPP flap, severe block flow on one side, major loss of power. I’ve seen cars ruin their engines the same way and I was lucky but wasn’t about to have it happen again and lose my motor. Thankfully no damage to engine. Now they’re gutted, LG Pro headers, NPP exhaust, gutted on my SC’d. No stink at all, no power gain with them removed judged by seat of pants, very small Db increase. I’m happy to have peace of mind one less thing to worry about.
Le Mans Master
Joined: Oct 2010
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From: cold & windy
i punched out my 3" ARH high-flows after 7yrs & 30k boosted miles @ 530h/540t because i was adding another almost 150hp to the build & didn't want to risk blowing them out & popping the engine.
i'd never had a problem with them beforehand, but when i took the mid-pipes out just to see, the elements were a little loose/shaky in there, so that's what finalized my decision.
the sound ain't much different with my LTs & dual 3" anyway. i've rarely noticed the smell very slightly. my truck's just a little smellier because it has side-exit exhaust just behind the passenger door. that can also be dealt with a little bit in the idle tuning, from what i understand.
i'd never had a problem with them beforehand, but when i took the mid-pipes out just to see, the elements were a little loose/shaky in there, so that's what finalized my decision.
the sound ain't much different with my LTs & dual 3" anyway. i've rarely noticed the smell very slightly. my truck's just a little smellier because it has side-exit exhaust just behind the passenger door. that can also be dealt with a little bit in the idle tuning, from what i understand.