Like all systems in a car, a proper exhaust system is needed to help maintain the performance of an engine. Besides avoiding a ticket a proper muffler is needed to help build the correct backpressor needed to keep an engine well tuned. I am sure you have all heard about the catalytic converter and the costly expense of replacing it. Without the catalytic converter you will not be able to pass the e-check.  Most catalytic converts last a long time, however, they can go bad.  If a car’s enigne is running poorly it can clog the catalytic converter. As exhaust leaves the engine it needs to get through the catalytic converter and muffler and exhaust to the atmosphere. A clogged converter reduces the flow in the exhaust system and can create a buildup in pressure back on the engine. With a bad converter you will see a decrease in fuel economy, backfiring, and possible over heating of the converter itself causing the inside to melt. Almost common ways trust your check engine light. A car that is starting to have problems with the catalytic converter will have a number of check engine light errors. One of the problems is a failing or defective Oxygen Sensor. Even if you takecare of your car there is ging t be a day thatthe converter will need to be replaced. The good news is that I have seen cars with well over 100,00 iles that still have their original catalytic converter.