One is a flat surface gasket. Another type uses a ball and socket with springs to maintain pressure. This type allows some flexibility without breakage of the seal or the manifold. A third type is the full ball connector type, which also allows a little flexibility. The muffler serves to muffle the noise coming out of the engine.
Exhaust gases leave the engine under extremely high pressure.
If these gases escaped directly from the engine the noise would be tremendous. Therefore, the exhaust manifold sends the gases to a muffler where they go through metal plates, or tubes, with a series of holes. The pressure of the gases is reduced when they pass through the muffler, so they go out of the tail pipe quietly. Made of metal, the muffler is located underneath the body of the car. It is connected between the tail pipe and the catalytic converter.