I am trying to take off my muffler. What does that little wire connected to the pipe right in front of the cat do? I am cutting the muffler about 4 inches back from that. Is this going to hurt anything???

 

that is for your o2 sensor. youi need it or it will throw a CEL and a hurt you mileage bad

 

That's an O2 sensor wire...

 

Well yeah, but it will still be on there. Just everything behind will not.

 

Well alrighty then. And now you know what that wire does. No harm, no foul.

 

So you guys are saying, no muffler=bad mpg??

 

Nope. Nobody said that. I think 96_XJ was saying that if you disable/remove the O2 Sensor then you will have bad MPG. Now that you mention it, total removal of the muffler is not the best idea. The backpressure caused by the presence of a muffler/exhaust system is good for engine performance.

 

Back pressure does not exist in the exhaust world... It is a matter of getting the correct piping...

It is like sticking your finger over a hose. Completely open it runs slow out the tip, you constrict it a little you now make the water force its way out faster, you constrict it to much you now cog the system. once you get the correct pipe size (about 2.25-2.5") you can run strait pipes and not feel any lose in power. going to 2.5" most of the time you pick up power.

 

...so it's less about backpressure and more about resonance?

 

it is about neither. it is about flow rate.

air and gasses are considered a fluid. So you need to treat them in equations and examples as such.

All a muffler does is disrupts the air to make its sound a desired tone (most of the time a deeper or quieter tone) it does no disrupt the flow rate tho.

 

Ahhh, ya' just gotta love science. I think we've delved deep enough. Thanks for the lesson.