A mixing subassembly for an exhaust gas system of an internal combustion engine for mixing exhaust gas which is discharged by an internal combustion engine with reactant, comprising a mixing path which extends in the direction of a mixing path longitudinal axis with an upstream mixing path inflow region for receiving exhaust gas and/or reactant in the mixing path, wherein the mixing path comprises a core flow channel, through which a first exhaust gas partial flow (T 1) flows, and a bypass flow channel, through which a second exhaust gas partial flow (T 2) flows, wherein at least one flow blocking element (38, 38') which reduces a flow cross section of the bypass flow channel is arranged in the bypass flow channel, wherein the bypass flow channel comprises a covering flow channel which annularly surrounds the core flow channel and wherein at least one flow blocking element (38, 38') comprises a flow blocking ring which is arranged in the covering flow channel, wherein the mixing path comprises an external mixing path housing which delimits the covering flow channel in a radially outward manner and separates it from the covering flow channel and an internal mixing path housing which delimits the core flow channel in a radially outward manner, wherein at least one flow blocking element is secured to an inner side, which faces the covering flow channel, of the external mixing path housing so that, between the flow blocking element and an outer side, which faces the covering flow channel, of the internal mixing path housing, there is formed a throughflow region with a flow cross section which is reduced with respect to a flow cross section of the covering flow channel upstream of the at least one flow blocking element and with respect to a flow cross section of the covering flow channel downstream of the at least one flow blocking element, characterized in that - at least one flow blocking element is secured to the outer side, which faces the covering flow channel, of the internal mixing path housing so that between the flow blocking element and the inner side, which faces the covering flow channel, of the external mixing path housing, there is formed a throughflow region with a flow cross section which is reduced with respect to the flow cross section of the covering flow channel upstream of the at least one flow blocking element and with respect to the flow cross section of the covering flow channel downstream of the at least one flow blocking element, and - at least two flow blocking elements (38, 38') are secured alternately to the internal mixing path housing and the external mixing path housing in a successive manner in the direction of the mixing path longitudinal axis. - at least one flow blocking element is secured to the outer side, which faces the covering flow channel, of the internal mixing path housing so that between the flow blocking element and the inner side, which faces the covering flow channel, of the external mixing path housing, there is formed a throughflow region with a flow cross section which is reduced with respect to the flow cross section of the covering flow channel upstream of the at least one flow blocking element and with respect to the flow cross section of the covering flow channel downstream of the at least one flow blocking element, and - at least two flow blocking elements (38, 38') are secured alternately to the internal mixing path housing and the external mixing path housing in a successive manner in the direction of the mixing path longitudinal axis.