Exhaust manifold muffler for an internal combustion engine

An exhaust manifold muffler for a multi-cylinder internal combustion engine comprising:

• an exhaust manifold portion including a plurality of manifold pipes, each having an upstream end, an intermediate portion and a downstream end, wherein each of the upstream ends of the manifold pipes is connected to a respective cylinder of the internal combustion engine and each of the downstream ends is spaced from the other downstream ends and wherein the manifold pipes are arranged in parallel with each other and in a row;
• and
• a muffler portion including a muffler housing defining a first muffler chamber, each of the downstream ends of the manifold pipes extending tangentially into the first muffler chamber so as to produce a swirl of exhaust gases in the first muffler chamber, a swirl pipe arranged in the first manifold chamber and extending in a semicircle from an upper portion of the first muffler chamber and a lower portion of the first muffler chamber, the swirl pipe having an inlet end that faces the swirl direction of the exhaust gases and an outlet end which is located between and faces the same direction as the downstream ends of the manifold pipes, and wherein the first muffler chamber is enlarged in cross-section compared with the manifold pipes.