Running without Cats
Thread Starter
Racer
Joined: Feb 2005
Posts: 320
Likes: 1
From: San Jose CA
Running without Cats
What would it take to run headers without the cats? I'm sure the PCM would start throwing codes all over the place. Would there need to be computer changes? O2 sensor changes?
Melting Slicks
Joined: Jul 2001
Posts: 3,284
Likes: 3
From: Southwest Florida
You'd need to run O2 simulators for the O2 sensors downstream of the cats. My recommendation: don't do it. You might gain 5 HP but the stench will almost knock you over. Modern (lean idling) cars smell horrible when the cats are removed and it isn't just a "smell" either, it's a nasal stinging/burning odor almost like muriatic acid!
Mike
Mike
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
You will find that most cats do not like being near the headers, between the fumes and forced hot air they really don't like being under there especially during the summer months.
Now dogs on the other hand.....
Sorry, couldn't resist. 
Now dogs on the other hand.....
Sorry, couldn't resist.
Thread Starter
Racer
Joined: Feb 2005
Posts: 320
Likes: 1
From: San Jose CA
Originally Posted by mikeyc6
You'd need to run O2 simulators for the O2 sensors downstream of the cats. My recommendation: don't do it. You might gain 5 HP but the stench will almost knock you over. Modern (lean idling) cars smell horrible when the cats are removed and it isn't just a "smell" either, it's a nasal stinging/burning odor almost like muriatic acid!
Mike
Mike
Hmm... The real reason I don't want to run the cats is that it'll be cheaper to get headers without them. I can get the cats later and bolt them on at smog time (year 2011).... The 5hp increase is just gravy and not really a concern for me. But if the smell is as bad as you say, I'll need to reconsider. This is going to be my daily driver afterall. Anyone else comment on this?
Thread Starter
Racer
Joined: Feb 2005
Posts: 320
Likes: 1
From: San Jose CA
Originally Posted by prc6vette
You can afford a C6 but can't spring for the extra couple of hundred dollars for cats? 
Save-up & be environmentally responsible.
Save-up & be environmentally responsible.
If I were environmentally responsible, I'be be driving a(n) insight/prius/<insert hybrid econobox> that gets 50 miles to the gallon. And so would you.
To say I can get it for less, isn't to say I can't spring for it.
Constructive comments please? I'd like to stay on track.
Racer
Joined: Jun 2005
Posts: 327
Likes: 0
From: San Ramon CA
Originally Posted by Virt
If I were environmentally responsible, I'be be driving a(n) insight/prius/<insert hybrid econobox> that gets 50 miles to the gallon. And so would you.
Spewing out mondo pollution for "maybe" 5+ HP is crap.
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Melting Slicks
Joined: Jul 2001
Posts: 3,284
Likes: 3
From: Southwest Florida
Back in my "younger days" when I wasn't as environmentally conscious, I tried running without the cat on my 95 Trans Am (LT1). The smell was so horrible that it would literally take your breath. If the air was moving just right when you opened the door so that the exhaust was coming up under the car a little, it would literally choke you just like it would if you sniffed over a bottle of concrete cleaning acid. It was so bad that I bought a high flow cat within about a week and installed it, vowing never to make a stupid mistake like that again.
Mike
Mike
Thread Starter
Racer
Joined: Feb 2005
Posts: 320
Likes: 1
From: San Jose CA
Originally Posted by mikeyc6
Back in my "younger days" when I wasn't as environmentally conscious, I tried running without the cat on my 95 Trans Am (LT1). The smell was so horrible that it would literally take your breath. If the air was moving just right when you opened the door so that the exhaust was coming up under the car a little, it would literally choke you just like it would if you sniffed over a bottle of concrete cleaning acid. It was so bad that I bought a high flow cat within about a week and installed it, vowing never to make a stupid mistake like that again.
Mike
Mike
Yowza.... well that's food for thought. Thanks mike.
Burning Brakes
Joined: Mar 2003
Posts: 1,030
Likes: 0
From: Pittsburgh PA
I've been running my '02 w/o cats for years. I never smell the exhaust because I'm always in the car driving when the engine is running. Better gas mileage and more power. Listen to the tree huggers if you want but I say make your own decisions.
Racer
Joined: Jun 2005
Posts: 327
Likes: 0
From: San Ramon CA
Originally Posted by aaaaa
I've been running my '02 w/o cats for years. I never smell the exhaust because I'm always in the car driving when the engine is running. Better gas mileage and more power. Listen to the tree huggers if you want but I say make your own decisions.
Melting Slicks
Joined: Jul 2001
Posts: 3,284
Likes: 3
From: Southwest Florida
Originally Posted by aaaaa
I've been running my '02 w/o cats for years. I never smell the exhaust because I'm always in the car driving when the engine is running. Better gas mileage and more power. Listen to the tree huggers if you want but I say make your own decisions.
Mike
Drifting
Joined: Nov 2004
Posts: 1,923
Likes: 62
From: California
No Cats... No Way
Originally Posted by Virt
What would it take to run headers without the cats? I'm sure the PCM would start throwing codes all over the place. Would there need to be computer changes? O2 sensor changes?
Just a sick smelling exhaust fumes especially if your car is a daily driver. Dont do it.