View Full Version : No cats, Pros and cons
07-03-2011, 03:03 PM
Check engine light came on and i need to replace the cats but i was thiken. Could i just get them cut out and the light would go out. Dont know a whole lot about it. I wanna keep my true dual 40 on it just cut the cats off.. Whats the pros and cons of running no cats and will it make my check engine light go off?? And we dont have inspection in SC so that is no problem
07-03-2011, 03:08 PM
no cats will make the check eng light stay on all the time as it monitors the rear o2 sensors to see if the cat is functioning correctly...and w/o cats it gonna see the same as the upstream o2 sensor and trip a light
only way to take the cats off and not have a light is to get it custom tuned so that the computer doesnt read the rear o2 sensors
also w/o cats the exhaust will be louder than it is now
07-03-2011, 03:16 PM
Im cool with louder exhaust. Al long as it sounds good not annoying loud. What about performance. Will it affect mpg? cant you get the o2 sensors welded into the pipe??
07-03-2011, 03:20 PM
The rear O2 sensors monitor cat operation. If the cats are gone, the light will be on. As mentioned, you will need an "off road" tune to make the light stay off. You can delete EGR at the same time :D
The tune is about the same cost as a new wye pipe, the increased power and economy are included at no extra charge.
07-03-2011, 03:23 PM
with your muffler i dont think it would be to bad...but it will be a good bit louder
you can get the o2s put back in but they will be pointless at the only thing they do is to monitor the exhaust to see if the cat is working properly, so if they are reading the same as the upstream o2 sensors..it will w/o cats, the computer thinks that the cat is not working properly and will set a p0440 code i believe for cat converter efficiency
only way to delete cats and not get a light is to get custom tune done so that it tricks the computer to thinking that the rear o2 sensors are working properly
07-03-2011, 09:07 PM
So removal of cats is worse MPG
07-03-2011, 09:13 PM
Incorrect, When i had my Cat cut off my 93 i felt a tad more power, and or if not better mpg not a huge difference but it did not hurt any
07-03-2011, 09:22 PM
40's and no cats is the way to go. just run some headers and it will sound pretty mean.
07-03-2011, 10:29 PM
Modern cats are not restrictive enough to flow to really hurt power or mpg. The only thing they have an affect on is your emissions and a slight effect on sound. The difference in hydrocarbons comming out the tail pipe is enormous though.
07-05-2011, 07:38 AM
you get no noticeable gains from gutting the cats. and if you search on ebay for carsound you'll see a ton of converters on there for dirt cheap. they're magnaflow cats and are great. i had 2 on my camaro...383 stroker with a radical cam. they stopped the gas smell from coming out the tail pipe...and with as cheap as they are it's worth saving the environment for 50 bucks.
07-05-2011, 11:08 AM
You'll only notice a gain in power if they're clogged. You can buy Thunderbolt cats with an O2 bung already welded on so just hook up the sensor and go, no need for a tune if you don't want one yet.
07-05-2011, 05:37 PM
don't be a tree hugger... just delete them and buy a tune.
07-05-2011, 06:37 PM
Def not a tree hugger i just didnt wanna lose mpg.. times are tuff
07-05-2011, 07:42 PM
I have cats on my truck, they are Magnaflow, from what I read they are supposed to flow pretty good. But I may be getting rid of them soon.
07-05-2011, 09:30 PM
you won't lose any MPG. you might gain a bit.
08-03-2011, 09:19 PM
So is the adjustment to the tune strictly for the check engine light...or is there any actual tuning advantage/disadvantage to losing them?
08-03-2011, 11:16 PM
This is an old post, but i've read somewhere you can get fake O2 sensors that trick your computer into thinking its running right, don't take my word for it though
08-04-2011, 10:41 AM
No need to not have cats, If they are clogged or failed , get off your cheap ass and replace em, but fix the problem that caused em to fail to begin with, You guys who remove your cat's are not doing the hotrodders and sport truckers any favors with the government, Just because you don''t have emissions now, just wait, its coming. The fedsand states and local governments are finding ways to squeeze every last dollar out of your hands.
08-04-2011, 02:07 PM
You guys who remove your cat's are not doing the hotrodders and sport truckers any favors with the government, Just because you don''t have emissions now, just wait, its coming. The fedsand states and local governments are finding ways to squeeze every last dollar out of your hands.
He speaks the truth. Please keep this in the forefront of your mind before getting all bent out of shape about cats being bad, restrictive, and robbing mpg. Just because the state you live in doesn't inspect, doesn't mean you aren't committing a federal offense. Replacement cats have become so cheap now that it's a smart move to keep them under there for the near future when your state does decide to make some more revenue and model themselves after the states that do inspect.
08-04-2011, 05:04 PM
sooooo? anyone want to actually answer the question?
JK: thanks for the input guys. Seems like something simple to replace...I just didnt want to chop up the new Y-pipe if it wasnt neccesary.
08-04-2011, 05:08 PM
keep them under there for the near future when your state does decide to make some more revenue and model themselves after the states that do inspect.
i agree.. more and more states are changing their laws. just think in a couple of years you could be required to pass California emission standards like a few other states are doing. on newer vehicles with stock cats in good order you "may" louse 1-3 HP if that, not enough to notice. it was like back in the late 60's when they came out with the air injection system on vehicles. everyone was saying the air pumps were robing HP from the motor. the alternators were taking more HP to turn than the single vane air pumps..
IMO- you can still get excellent performance out of a vehicle, and still be smog legal..my .02
08-04-2011, 05:11 PM
:lol: Fvck the god damn government, I'll do what I want with my personal truck. Hundreds of cows farting all day can't be any better than my truck running without 2 metal cases with precious metals in them.
Edit: Fvck that emote too, it takes to long to go advanced and find it.
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