An assembly can include a valve seat for an exhaust bypass valve of a serial turbocharger system where the valve seat includes a base portion and a wall portion that extends axially away from the base portion; and a gasket that includes a planar portion that defines a perimeter and a socket disposed interior to the perimeter, where the socket includes a valve seat surface axially recessed from the planar portion and configured to position the seat. In various examples, the valve seat is positioned in the socket of the gasket and fixed to the gasket. Various other examples of devices, assemblies, systems, methods, etc., are also disclosed.