There are some main differences between performance exhaust systems and straight pipes in looks and sound output while the engine is running. For those who want to spruce up their ride, the performance pipes are the way to go; if you want loud and proud, you'll want the straight shooters. You will have to think about noise laws, as well as emissions laws, when making a straight pipe exhaust on your vehicle, though. Any violation of these laws can carry penalties and could result in fines that vary from state to state.
When making a choice between straight pipes or performance exhaust systems, you have to take into account the differences in the vehicle’s power curve. The back pressure from using a performance exhaust system keeps the low pressure fumes from escaping out of the vehicle. When you cut a straight pipe, which generally involves removing the catalytic converter and muffler to make the vehicle louder, you remove the back pressure that keeps the air-fuel mixture from escaping the fire chamber in that moment the valves switch position. Your straight pipe has no back pressure and allows sound, pollutants, and your gas mix to escape through the exhaust pipe, causing a lower power curve on your engine from the escaping gases.
Performance exhaust systems keep the back pressure high, which increases the curve of output from your engine, as no pressurized gas can escape before it is pulled back into the fire chamber as the valves switch position. Louder exhaust pipes are generally from modified straight pipe systems which, in many cases, violate vehicle emission standard laws and noise ordinances.
Flexibility of Appearance
A straight pipe system can sound better than performance exhaust systems, but performance systems come in many shapes and sizes. Chrome plating and fancy exhaust ends for your performance exhaust can be quite the improvement on your vehicle’s look. A straight pipe system can be extended and dressed up with these chrome fittings for appearance as well, but usually these modifications are discarded in favor of a simply cut pipe that’s left hidden under the vehicle.
You will see a lot of performance exhaust systems at car and truck shows around the country with variances and customizations in some cases to make the vehicle stand out from the crowd. Performance systems will sometimes be modified to allow for more noise output to mimic the straight pipe sound, and the look of the exhaust system can be modified a lot from its original style while still giving the same functionality.
The key point is that the straight pipe systems have some benefits, yet they lack in flexibility. Some people believe that a straight pipe system can affect the engine by removing the back pressure, but the power curve of your engine will decrease as a result; however, this will also result in more pollutants emitted into the air, which might get you a ticket. Performance systems can provide a good alternative since they are actually very flexible in both performance and appearance. With a little know-how, you can modify a performance system to do a lot of this same stuff without polluting the environment or the neighborhood with too much engine noise.