Oh...sorry sorry bro zach, OK I will try to explain how the exhaust system work ^_^.
Exhaust system have 3 main structure, 1)exhaust manifold/extractor, 2)catalytic convertor, 3)silencer/muffler. All this 3 structure are connect with exhaust pipe. So how it works?
1)exhaust manifold, help engine easier to push out the exhaust gas. In the first wave of exhaust stroke, the exhaust valve on the engine will open, then piston push out the high presure exhaust gas, then follow by second wave exhaust stroke, but this time the exhaust gas not only be push by the piston, it also suck by the first wave of exhaust stroke, make the engine more easy to push out the exhaust gas, then the exhaust gas act like a pulse, one by one be suck out from the exhaust pipe.
Original engine spec, all cyclinders are using the same exhaust manifold, so it can create the exhaust pulse very fast, make maximum torque output came very soon, help the car faster to pick up in low range RPM. But if the RPM keep increasing, the exhaust pulse will overlap each other and create back presure.
(b'cause all cyclinders are using the same exhaust manifold. That is why other people say need some back presure to make the car easy to pick up) The back presure will limit the engine maximum power output.
To unlock the true power of the engine, all cyclinders are using individual pipe with the same lenght, then all connect to a single pipe again in order to reducing the amount of back presure, now the engine can release the true power of it. But before this, the exhaust wave must reach certain RPM speed to create the exhaust pulse, which mean the maximum output will be in high range RPM, same time the torque of low range RPM will be weaken and focus on high range RPM.
2)catalytic convertor, a pollution control device installed in the exhaust system that converts harmful combustion gases into carbon dioxide and water vapor by means of a heat-producing chemical reaction. (sourse from
Midas Mufflers, Brake Repair, Car Maintenance and Auto Repair Services) (I'm not good enought to explain it in english...very sorry bro zach...-_-!)
3)silencer/muffler, to cancel the niose came from cyclindres. This section will not effect the performance much. But it can act like a musical instrument of the car ^_^.
Exhaust pipe, changing the width of exhaust pipe will also effect the exhaust pulse. If the exhaust pipe is too width, exhaust pulse are hard to keep it form, then it will end up inside the exhaust pipe and create back presure. So don't trust bigger is better~^_^.
