Exhaust manifold for internal combustion engine

The manifold has gas inlet pipes (21-24) connected to an exhaust gas outlet pipe (14) using a tube (12). The outer inlet pipes (21, 24) have connecting flanges (26, 28), and inner inlet pipes (22, 23) are connected by a central double input flange (30) integrated with an output flange (38) of the pipe (14). The flange (30) is separated from the flanges (26, 28), and reinforcement webs (48-50) are integrated with inter-pipes (12a-12c).