hey everyone. I just purchased some cherry bomb extreme mufflers and tips for my true dual system. I want to gut the cats too, but I am worried about a few things and need some of your help. I notice one of the o2 sensors is in the cat, and on the other side the o2 sensor is in the pipe before the cat. If I gut the cats, where do the o2 sensors need to be placed in order for the computer not to get messed up, or can I leave them where they are?

 

Ok, first off, unless the cats are plugged or you are running a highly modified engine with performance cams or forced induction, you are not going to gain much if any noticeable power from removing or gutting the cats. I assume you want more sound however, and removing the cats will do that for you very well. You could go with a good high flow cat which will not be as loud as straight pipes, but if installed correctly, will be significantly louder than stock cats.

Second off, there is no O2 sensor placement that will address the CEL issue. Some may suggest O2 simulators, which is another issue entirely. O2 simulators are not legal in the US. I would like someone to point out where these can even be obtained, because I have not seen any on sale anywhere for over a year. It is not cheap to aquire them either, you can get a high flow cat for less. Some have said you can use a simple resistor, but this is an ignorant statement. The computer is looking for a lower voltage at the rear O2 sensor, and a resistor would do that, but the computer is also looking for a behavior. If you have a properly functioning catalytic converter, the signal will also be stable and not fluctuate up and down significantly. A resistor will not address this issue, the computer will most likely interpret the weak but erratic signal as a bad O2 sensor. It will also attempt a corrective strategy to correct the signal, which can cause bad fuel economy depending on the year and the exact model computer. I'm not saying it won't work in fooling the computer, but if it doesn't work, thats a lot of extra hassle and expense.

My advise, you be to either leave the stock converters alone. If it isn't broke, don't fix it. If the system is still too quiet for your liking then consider using a high flow cat as opposed to coming up with create ways to fool the computer. Now which converter you use should depend upon how you want to do the system. The best official way that makes the feds happy is to replace each factory converter with a converter. If this arrangement, you would use a high flow cat with a center O2 port. You could leave the factory pre cats in place or replace them with new pre cats, either way won't make a lot of different performance or sound wise. The method that is the loudest is to use a singe converter to replace both factory and place the O2 sensor behind the converters to keep the light off. Now some factory systems have only one cat on each bank, I am not sure of what year or model your truck is.

The cat that I would recommend for the deepest tone and maximum performance and volume is this
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Based upon your description of the system, I think there are O2 sensors you are not seeing. If there is a sensor in the cat on one side, there should also be a sensor in the cat or behind the cat on the other side as well, thats part of how OBD-II works. There will be O2 sensors somewhere before the cats on both sides as well, some are in the headpipe, other times they are in the manifolds.

 

Well I already have hi-flow cats, and I want to gut mine for sound only. My brothers had his hi flow cat gutted on his dodge ram 5.9L, and the o2 sensor is still in it and he had no problems, but it made his truck very very loud. I have OBD I, not II, so its a little dumber than II, and I am not missing any o2 sensors, there big and blue and brand new. I have a true dual, and theres one o2 sensor on each bank, on the left bank there is a o2 sensor in the cat, on the right bank there is an o2 senor before the cat.

 

Ok, there shouldn't be a sensor in the cat per se, but if your vehicle is OBD-I as you say, no, you will not mess up the O2 sensors or the computer by running without cats. Just try to keep them that same distance from the engine as the originals, this ensures the correct readings and a rapid warmup.

 

ok cool sounds sweet. Thanks Bearriver

 

My truck is a 1992 ford f-250 with a 460 and it hasnt had cats on it since I bought it, I even bought it without cats. Its ran fine since day the day I bought it and I've had no problems out of it.

 

awsum thank u for info