A secondary air injection or SAIR system is illustrated and described which includes a first air injection path defined by in part by a lower ditch formed in the head mounting surface of the cylinder block, and a second air injection path defined in part by a second ditch formed in the block mounting surface. The cylinder head gasket is used to separate and seal the first ditch from the second ditch. The first and second air injection paths are separate and isolated from one another such that secondary air may be selectively introduced through the first air injection path into the first exhaust leg and selective introduced through the second injection path into the second exhaust leg independent of the first air injection path.