[I]They only do damage to Human ear drums. & Fuel consumption varies due to driving Thrill - over the produced noise !
OEMs are not stupid to put in certain size mufflers between Exhaust manifold to final tail pipe.
The Main purpose of exhaust system in an engine is to throw away the burn out gases as fast & silently as possible.
a choked silencer / exhaust system over heats the engine, consumes more fuel and downgrade the performance in terms of pick-up.
Bigger the exhaust pipe size, faster gas blows away, making HIGH pitch noise at abrupt aka spontaneous acceleration.
After market exhausts are produced to get max performance with less of Silencer affect. It minimize the under carriage road clearance of the vehicle.
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