A gas generator assembly, comprising: a gas generator including: a substantially cylindrical housing comprising a gas exhaust port and containing: a stack of substantially cylindrical gas generant wafers located within a closed chamber within the housing, the chamber in communication with the gas exhaust port; igniter material adjacent the stack of gas generant wafers adjacent one end of the housing; an initiator operably associated with the igniter material and communicable with an exterior of the housing; the gas generator assembly characterized by: a plurality of laterally adjacent and laterally and axially supported stacks of substantially cylindrical gas generant wafers located within the chamber within the substantially cylindrical housing in spaced relationship to and free from contact with structure of a side wall of the substantially cylindrical housing, at least some of the plurality of laterally adjacent gas generant wafer stacks being: laterally supported by lateral support structure extending axially along a length of a respective stack and located inwardly of the side wall of the housing, substantially contacting the respective stack on at least a part of a circumference thereof and supporting each stack against rotational movement within the substantially cylindrical housing; and axially supported at opposing ends by axial support structure (40, 40') contacting gas generant wafers of the respective stack; the gas generant wafers of the stacks formulated and in combination to, upon ignition, generate a gas within the chamber of a pressure in excess of ambient; and igniter material adjacent the plurality of laterally adjacent stacks adjacent one end of the housing; the substantially cylindrical housing comprising at least one closed gas exhaust port (80, 82) in communication with the chamber adjacent an opposing end of the laterally adjacent stacks, the at least one closed gas exhaust port (80, 82) configured to open to release the gas to an exterior of the substantially cylindrical housing in response to substantially a predetermined pressure within the chamber above ambient pressure. a gas generator including: a substantially cylindrical housing comprising a gas exhaust port and containing: a stack of substantially cylindrical gas generant wafers located within a closed chamber within the housing, the chamber in communication with the gas exhaust port; igniter material adjacent the stack of gas generant wafers adjacent one end of the housing; an initiator operably associated with the igniter material and communicable with an exterior of the housing; a stack of substantially cylindrical gas generant wafers located within a closed chamber within the housing, the chamber in communication with the gas exhaust port; igniter material adjacent the stack of gas generant wafers adjacent one end of the housing; an initiator operably associated with the igniter material and communicable with an exterior of the housing; the gas generator assembly characterized by: a plurality of laterally adjacent and laterally and axially supported stacks of substantially cylindrical gas generant wafers located within the chamber within the substantially cylindrical housing in spaced relationship to and free from contact with structure of a side wall of the substantially cylindrical housing, at least some of the plurality of laterally adjacent gas generant wafer stacks being: laterally supported by lateral support structure extending axially along a length of a respective stack and located inwardly of the side wall of the housing, substantially contacting the respective stack on at least a part of a circumference thereof and supporting each stack against rotational movement within the substantially cylindrical housing; and axially supported at opposing ends by axial support structure (40, 40') contacting gas generant wafers of the respective stack; the gas generant wafers of the stacks formulated and in combination to, upon ignition, generate a gas within the chamber of a pressure in excess of ambient; and laterally supported by lateral support structure extending axially along a length of a respective stack and located inwardly of the side wall of the housing, substantially contacting the respective stack on at least a part of a circumference thereof and supporting each stack against rotational movement within the substantially cylindrical housing; and axially supported at opposing ends by axial support structure (40, 40') contacting gas generant wafers of the respective stack; the gas generant wafers of the stacks formulated and in combination to, upon ignition, generate a gas within the chamber of a pressure in excess of ambient; and igniter material adjacent the plurality of laterally adjacent stacks adjacent one end of the housing; the substantially cylindrical housing comprising at least one closed gas exhaust port (80, 82) in communication with the chamber adjacent an opposing end of the laterally adjacent stacks, the at least one closed gas exhaust port (80, 82) configured to open to release the gas to an exterior of the substantially cylindrical housing in response to substantially a predetermined pressure within the chamber above ambient pressure.