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What are the pros and cons of going without a catalytic converter

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Old 02-16-2017, 02:54 AM   #1
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Default What are the pros and cons of going without a catalytic converter

I been wanting to upgrade my exhaust. Right now I have the stock exhaust, manifolds, cat resonator and muffler. But I want to put headers, a flow master muffler and two tips out the back. But I want it to be loud really loud and everyone tells me to not install a cat but then I get people saying it'll work against my truck to not install one. So what are the pros and cons of going without a catalytic converter and going with one.
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Old 02-16-2017, 06:00 AM   #2
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Pros

Your Federally legal. Regardless of any local state laws that you may or may not have for inspection testing (visual or pipe "sniff), its a Federal law that states you cannot remove such equipment and legally operate the vehicle on public roads. The law is usually too busy with other police actions to pull cars over and inspect for this, so most folks simply get away with it. However, when you trade in a vehicle at a dealership or car lot, they make you sign a paper (one of the many you sign away with and most likely not pay attention to) that states all Federal mandated equipment is still on the vehicle. Its against the law for you to sell outright, or any dealer/car lot to sell a vehicle that is missing this equipment. A personal sale can allow the buyer to sue you later (even if you are selling the car "As is") and force you to buy back the vehicle, or re-install the missing Federal required equipment.

Cons

Same as above
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Old 02-16-2017, 06:02 AM   #3
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It can mess with certain sensors and back pressure through the exhaust manifold.

Last edited by RealQuiet; 02-16-2017 at 06:04 AM.
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Old 02-16-2017, 09:07 AM   #4
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real world, not the nonsense stated above:

If you are in a state with inspections it will be a hassle. The exhaust will stink. It will be louder. You won't have to worry about the cats going bad. The exhaust will flow better. This has more benefits for turbo vehicles like ecoboost. It will throw a check engine light unless it is tuned out or you use an O2 simulator.
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Old 02-16-2017, 09:23 AM   #5
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Originally Posted by RealQuiet View Post
It can mess with certain sensors and back pressure through the exhaust manifold.
Yes and no. Our vehicles have a 4 stroke engine and are not susceptible to changes in back pressure. Old wives tale. In fact, less back pressure means more power, to a point.

Pros

Slight increase in power
Slight change in sound (could be a pro or con)
Simplified exhaust system

Cons

No longer emissions legal (may or may not be an issue for you)
Will likely require a custom tune to deal with sensor and computer issues (can and has been done, especially with long tube headers)
You will likely have no noticeable gains for the lack of an expensive piece of equipment.

FWIW

Stacey David from the TV show Gearz did a segment where he built a vehicle and showed a negligible difference with and without cats on the dyno. He did this specifically to disprove the myth that taking off the cats makes a significant difference and to show that you can have both power and be more environmentally friendly.

IMHO

It is not worth the hassle unless you are building a serious power toy for off road use.

If it is sound you are after, simply run without a muffler and resonator and then dual tails out the back. Personally I like the sound and it is plenty loud. I really don't think you will see a big difference in sound, although there will be some.

To each his own but I don't think for what you want it is worth the cost and issues. There are plenty of loud, good sounding cat back systems out there.
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Old 02-16-2017, 01:32 PM   #6
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I believe that Bexar and the surrounding counties have emissions testing as part of the state inspection, and the vehicle wont pass without the cat. They plug in the tester into the OBD point and check for the O2 sensors, and that's also why some tuners have to go back to original to pass emissions.


Don't pass the inspection, don't get a license plate renewal.
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Old 02-16-2017, 09:20 PM   #7
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To summarize, there is one con: it's a violation of Federal law.

Everything else is a pro: less heat surrounding your transmission, better flow, more power, smoother throttle, less weight, no fears of clogged cats, no fears of a thief taking a saw to your truck after dark, etc.

But as mentioned, you'll likely want a tuner to disable the sensors so you don't get a code stored in the ECU.
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Old 02-16-2017, 09:54 PM   #8
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Removing them won't gain as much as many think. Power gain is less than 2% on 700 bhp Supercharged Coyotes.

Last edited by Gene K; 02-16-2017 at 10:54 PM.
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Old 02-16-2017, 09:59 PM   #9
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I believe that Bexar and the surrounding counties have emissions testing as part of the state inspection, and the vehicle wont pass without the cat. They plug in the tester into the OBD point and check for the O2 sensors, and that's also why some tuners have to go back to original to pass emissions.


Don't pass the inspection, don't get a license plate renewal.
Do they test 28 yo vehicles? It's not even OBD2.

Last edited by Gene K; 02-16-2017 at 10:01 PM.
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Old 02-16-2017, 10:01 PM   #10
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You wont need a Tuner or Emulators.
You don't have rear 02's to worry about.

Last edited by Gene K; 02-16-2017 at 10:44 PM.
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