The volume of exhaust flow is one of the important factor when performing sizing & selection of a silencer. The open flow area within the silencer must be large enough to accommodate the exhaust flow without exceeding the engine manufacturer’s allowable backpressure. If the silencer is much too large. then the exhaust noise simply passes through using only the initial large expansion for attenuation. On the other hand, insufficient size of silencer may cause loss of power and possible damage to the engine or equipment.