Two-passage exhaust system for an engine

An exhaust system for a vehicle having a turbocharger and a wastegate coupled to a bypass pipe comprising:

• an inlet receiving exhaust gasses;
• a housing comprising a first portion separated from a second portion by a common wall, said first portion comprising a first exhaust passage therethrough, said first portion receiving exhaust gasses at a first inlet of the exhaust system from the turbocharger, wherein the second portion comprising a second exhaust passage therethrough receiving exhaust gasses at a second inlet of the exhaust system from the wastegate and the bypass pipe and communicating exhaust gasses to a first outlet of the exhaust system, said second exhaust passage comprising a plurality of expansion chambers disposed in series within a continuous pipe from the second inlet of the exhaust system to the first outlet of the exhaust system, wherein each of the plurality of expansion chambers comprises a diverging wall and a converging wall, said diverging wall extending angularly outward from an expansion chamber inlet to an intersection with the converging wall, said converging wall extending angularly inward from the intersection to an expansion chamber outlet;
• wherein the plurality of expansion chambers comprise different volumes that decrease from the first inlet of the exhaust system to the second outlet of the exhaust system.