Patent ID: 7325396

Claim:
An exhaust manifold comprising: branch pipes that correspond to each cylinder of a multi-cylinder internal-combustion engine; a collection section that collects together end sections on the downstream side of said branch pipes and leads them to a downstream catalyst; a bypass path for joining the upstream side of said collection section with the downstream side of said collection section, and causes an upstream catalyst to intervene midstream; and an open/close valve that closes the exhaust path inside said collection section and leads an exhaust gas from an internal-combustion engine to the side of said upstream catalyst, while on the other hand, by opening that exhaust path, leads said exhaust gas to the side of said downstream catalyst; characterized in that when said open/close valve is closed, a path system is established such that exhaust paths for each of said collected branch pipes are independent from one another on the upstream side of said open/close valve inside said collection section.