A pyrotechnic inflator assembly comprising: a shell member having an inner surface, an outer surface, an open first end and a closed second end opposite the first end; an end cap joinable with the shell member to at least in part enclose the open first end of the shell member to form an inflator subassembly, the inflator subassembly containing a quantity of pyrotechnic material and at least in part defining a combustion chamber wherein at least a portion of the quantity of pyrotechnic material is reactable to form product gas for inflation of an associated airbag cushion and to generate pressure within the combustion chamber, the end cap at least in part containing an initiator that upon actuation initiates reaction of the pyrotechnic material; and an overwrap about at least a portion of the inflator subassembly, the overwrap comprising a composite of fibers and a resin matrix system, characterized in that additionally a diffuser assembly is disposed adjacent the second end of the shell member in an outwardly extending direction, the diffuser assembly including a plurality of flow control features for controlling flow of product gas from the inflator assembly; the overwrap extends about at least a portion of the inflator subassembly and the diffuser assembly to form the pyrotechnic inflator assembly that withstands the pressure generated within the combustion chamber upon reaction of the pyrotechnic material; and the shell member closed second end comprises breakout pressure-controlling scoring or the shell member closed second end comprises a seal disposed onto a shell member opening at the second end, wherein the diffuser assembly comprises: a central gas diffuser element and a controlling orifice element at least in part disposed between the central gas diffuser element and the second end of the shell member, the diffuser element comprising a plurality of product gas discharge openings. a shell member having an inner surface, an outer surface, an open first end and a closed second end opposite the first end; an end cap joinable with the shell member to at least in part enclose the open first end of the shell member to form an inflator subassembly, the inflator subassembly containing a quantity of pyrotechnic material and at least in part defining a combustion chamber wherein at least a portion of the quantity of pyrotechnic material is reactable to form product gas for inflation of an associated airbag cushion and to generate pressure within the combustion chamber, the end cap at least in part containing an initiator that upon actuation initiates reaction of the pyrotechnic material; and an overwrap about at least a portion of the inflator subassembly, the overwrap comprising a composite of fibers and a resin matrix system, characterized in that additionally a diffuser assembly is disposed adjacent the second end of the shell member in an outwardly extending direction, the diffuser assembly including a plurality of flow control features for controlling flow of product gas from the inflator assembly; the overwrap extends about at least a portion of the inflator subassembly and the diffuser assembly to form the pyrotechnic inflator assembly that withstands the pressure generated within the combustion chamber upon reaction of the pyrotechnic material; and the shell member closed second end comprises breakout pressure-controlling scoring or the shell member closed second end comprises a seal disposed onto a shell member opening at the second end, wherein the diffuser assembly comprises: a central gas diffuser element and a controlling orifice element at least in part disposed between the central gas diffuser element and the second end of the shell member, the diffuser element comprising a plurality of product gas discharge openings.