Automobile Silencer

It is useful in V engines in order to reduce back pressure. but in others like in Mahindra XUV it is just for nice appearance.

The pressure of the exhaust inside the exhaust pipe decreases as it reaches the "silencer". This is because the silencer acts as a larger chamber for the exhaust to expand in. As the exhaust expands, the backpressure is reduced. Theoretically, no matter how many "silencers" you have, the backpressure will remain the same in the end as long as the "silencers" dont have any form of backpressure creating material inside (such as fiberglass or stainless steel fill).

As the exhaust enters the "silencer" it expands, even if only for a second. That second allows the exhaust time to cool and shrink back as well. What you may be seeing isnt "silencers". You are probably seeing a catalytic converter, spark arrestor, and/or a muffler.