different exhaust systems

Im a little confused about the Types of exhausts ..I purchased a new one with a fixed flange and the one that came has a FLAT face connection.....

the manifolds from the engine appear to be fixed flange but have a recessed part around the pipe bit that sticks out a little....( The connection to silencer bit ..three bolts )

should I be using the compressed type gasket that Superformance sell ...or the solid ring I seem to have from somewhere....!! or am I totally mixed up....?

Thanks