What happens if you Remove the catalytic converter?

Answer 1

Before you read any further, I must tell you that removing the catalytic converter is illegal. I strongly advise that you DO NOT remove it.

You will be in violation of Federal and most state laws.

That being said, the biggest negative effect, as stated, is that is illegal. You will never pass emissions.

But if you don't have emissions tests, removing the catalytic converter will increase flow of exhaust from your engine, allowing the engine to run more efficiently. This means more power, and since the weight doesn't change, better fuel economy (usually).

But before you go chopping off your catalytic converter, it is important to know that on modern cars, there is an oxygen sensor after the converter to monitor it's performance. removing the converter will turn on the 'check engine' light.

Also, depending on your vehicle, the o2 sensor may also affect your fuel/air mixture, and may hurt both fuel economy and power.

One last thing to consider: There IS such a thing as too little restrictions on exhaust. Some engines need some back pressure to run efficiently. Removing the catalytic converter and the muffler, and increasing the diameter of the pipes too much will decrease the velocity with which the exhaust gases move, which will actually cause more restrictions on the engine.