Just wondering other then the CEL what other problems can I run into if I just chop the cats off and leave my cherry bomb on ? Any stalling? or high gas milege?

With the loss of back pressure, you'll lose some low-mid range power. As it has been mentioned in past posts, these engines are designed for some back-pressure to work at their most efficient range at various rpm's.

The speed-density system uses a MAP (barometric) sensor to tell the FI system the loads on the engine and utilizes the fuel map tables to calculate what the engine would need. The MAP essentially is reading manifold vacuum levels to determine Hg, rpm and % of throttle to apply the fuel map tables for the conditions in conjunction with O2 sensor readings.

Also, w/o the signal from the O2 sensors, the PCM doesn't have the data to properly monitor the oxygen content to determine in the engine is running the proper A/F ratio.

Considering that removing a perfectly good cat is an EPA violation subject to a fine of $10,000. Even swapping high flow cats is a violation, that would be hard to prove the original cats were bad or good, so the EPA overlooks this violation.There is little to be gained if any thing, and you may create a far costlier problem.You engine computer is designed to run with cats. DON'T DO IT!

Considering that removing a perfectly good cat is an EPA violation subject to a fine of $10,000. Even swapping high flow cats is a violation, that would be hard to prove the original cats were bad or good, so the EPA overlooks this violation.There is little to be gained if any thing, and you may create a far costlier problem.You engine computer is designed to run with cats. DON'T DO IT!


some states like South Carolina do not have emmission constraints. or testing for that matter. There are far wors things than my car without CATS. I think this would be state specific right?

If this were 1980 something and you cut the cat off your 360 powered Dart.you would probly gain some HP.Truth is ALL modern performance engines are designed to run their best with cats.So even if it is legal to cut them out,it just aint worth it.

Still if I go ahead and do it regardless! Can I drive daily with the CEL on or even if i get the codes cleared without messing anything up major in my engine lmk? thanks

They have discontinued tail pipe testing in my area, this doesn't mean I have the freedom to remove my cats.The epa is a federal regulation. Just because your state doesn't have testing laws in place doesn't mean the cars sold in that state don't have to follow epa regulations.

I don't know if I understand what is to be gained by removing the cats, to be honest. There are plenty of good exhaust options out there, that leave the cats in place, and add hp/torque. If it's sound you want, just get cutouts.

I guess I'm just missing why you would want to remove them. High-flow cats are one thing, but to just take them off? I think you would end up with drive-ability issues, not to mention it's against Federal Law.

Only way I could see it is if you were making this a track only car with serious mods, but essentially making it so it's no longer street-legal.

The biggest cork in the exhaust system are the catalytic converters. This was confirmed by the SRT engineers in a few chat sessions. There are couple of members here (TooFart I believe...) who has no cats on his car, and it made a significant improvement.

If I was going to mod an R/T (which I do not have --- YET...) I would leave the stock mufflers in place, and go with a catless mid pipe.

Other than the legal ramifications, I'd have one concern;

It's all about the location and number of the O2 sensors from what I am told. Someone can probably chime in who knows more about it than I do, but my understanding is that if you have upstream and downstream sensors, the computer will recognize the post-cat sensors registering the same exhaust condition as the pre-cat sensors. In addition to kicking CEL, the computer will hunt to find the proper A/F ratio in the meantime. I don't think the car will run correctly and may not run well at all.

I don't know the O2 locations on a Challenger. On my Ram I believe there are upstream and downstream sensors, so I'm guessing the Challenger has them as well.

Personally, it seems to me that the potential problems and issues outweigh the benefits of removing cat converters on a modern, computer controlled car.

Just out of curiosity.....what are you hoping to gain by removing them? I'm assuming more power?

I don't know the O2 locations on a Challenger. On my Ram I believe there are upstream and downstream sensors, so I'm guessing the Challenger has them as well.

It does the 'upstream' O2 is in the cat body, the 'downstream' one is in the exhaust downpipe after the cat, for a total of four O2 sensors.

I went from 12.99 to 12.52 by removing the high flow cats with off road mids and a 15% richer mixture.