Is there much differences in HP or TQ?
Should I delete cats?
Melting Slicks
Joined: Apr 2007
Posts: 3,290
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From: Willow Springs IL
It is technically illegal to use aftermarket cats because they are not in the factory location. I would just take them off if you are doing a long tube header exhaust. The car will smell a little bit, but I kinda like that old musclecar smell anyway.
Race Director
Joined: Oct 2005
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From: Saint Albans, WV
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Instructor
Joined: Jul 2006
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From: Redondo Beach CA
And in my experience I ran my car without cats for a little while until I could get my exhaust guy to fab them into my system. It stunk to high hell, and between dyno runs there was less than 4HP difference between running with cats and without.
The whole punch out the cats thing is really unnecessary in anything but super high CFM situations that you'll almost never see on a street setup. Modern high flow cats are so efficient it's just silly to run without them.
Race Director
Joined: Aug 2005
Posts: 13,592
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From: Hudson WI
NCM Sinkhole Donor
I don't get the smell issue. When cats first came out in 1973 or 4, everyone complained about the "rotten egg" smell, now people are complaining about the smell without cats!
Burning Brakes
Joined: Aug 2007
Posts: 962
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From: SPRING HILL FL
You have enough info now to make a decision. If I paid for something I would use it. Some guys buy the headers without cats and save the money.
If you are not going to use them, care to sell them?
If you are not going to use them, care to sell them?
Melting Slicks
Joined: Feb 2004
Posts: 3,131
Likes: 148
From: Sugar Land TX
1975 was first year for production cars with cats. I think the reason for the "rotten egg" smell is when people used leaded gas in their catted cars. They sold both leaded and unleaded for several years. The leaded was a tad cheaper so some people would buy the cheapest.
Race Director
Joined: Jun 2005
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From: Phila Suburbs 2023 C8 & 2013 650ix
Also, the oil companies used a sulfur additive and that combined with high sulfur fuel caused the generation of hydrogen sulfide which smells like rotten eggs.
And from the EPA website:
Using its authority under the Clean Air Act, EPA promulgated comprehensive regulations which will reduce sulfur levels in gasoline and diesel fuel. These are Federal programs which are national in scope. Vehicles meeting the Tier 2 emission standards (car, vans, pickup trucks and SUVs) are much cleaner - 77% to 95% cleaner, depending on the size of the vehicle-compared with model year 2003 and earlier. The new standards also reduce sulfur content of gasoline by up to 90%. The public health and environmental benefits of this program (more than $25 billion) far exceed the costs to consumers (2 cents/gallon and $70 to $250 per vehicle). EPA estimates that this program will prevent as many as 4,300 deaths, more than 10,000 cases of chronic and acute bronchitis, and tens of thousands of respiratory problems a year.
Last edited by Walt White Coupe; Oct 9, 2010 at 03:36 PM.
Le Mans Master
Joined: Aug 2010
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From: Central Texas
Burning Brakes
Joined: Oct 2006
Posts: 995
Likes: 2
From: Virginia Beach VA
Keep 'em
No advantage on street what-so-ever, cats burn unignited fuel, & you'll definately smell or worse to the point of irritating your eyes. Headers add enough sound with stock muffs, but after markets can get plain obnoxious w/ headers. Had Flowmasters & added headers considerbly louder, w/ NPPs open embarrissingly loud at WOT, but in good way. Had cats the whole journey all the to 450 rwhp. A non-catted car sounds like a 60s hotrod thru the floor, not flattering for an expensive best American sports car.