Though the car is the result of complex engineering as a whole some of the most complex engineering goes into the car's engine. It is amazing though how people will find simple and elegant ways to understand what is going on and learn how to make things better.
For example amidst all the many things that are happening while your car's engine is running the exhaust gases that are produced when the fuel burns are constantly being thrown out. Something similar to our exhaling air as we perform respiration. Now imagine once you have inhaled air you are not able to exhale it easily. What will happen is your breathing will become labored and heavy and if at the time you are carrying out an energy intensive task such as running or climbing your ability to perform the task will be compromised.
A car's engine is always performing a strenuous task. Even if your car seems to perform effortlessly. Therefore any impediment to ejecting the exhaust gases affects its performance negatively. On the other hand anything that facilitates the quick and efficient removal of the exhaust gases helps to improve the engine performance.
Exhaust headers help improve the engine performance by making the exhaust gases exit faster. In a stock engine the exhaust gases from the several cylinders are brought together and then made to exit. This is not very optimal because the cylinders let out the exhaust gases at varying times. Exhaust headers on the other hand carry the gases directly to the exhaust pipe from each cylinder. This lets each cylinder eject the gases without any hindrance.
This ability to exhale more easily makes the engine roar with life. When the engine is performing at the higher output region the quick ejection of exhaust gases is very useful. This is because when in the high power mode the amount of exhaust gases produced is also high.
If you want to improve the performance of your car, exhaust headers are a great option. You can get exhaust headers online just as you can get other car aftermarket products such as body kits. You can get more information and also evaluate the options available for your car.