A system (100, 200) for treating exhaust gas of an internal combustion engine, comprising: a first aftertreatment component having a first central axis and a first axial extent, a second aftertreatment component having a second central axis and a second axial extent, and a third aftertreatment component having a third central axis and a third axial extent; wherein the first, second, and third central axes are substantially parallel; wherein at least a portion of the second axial extent and the third axial extent are shared with the first axial extent; a first end cap at a first end, the first end cap defining a first fluid chamber that fluidly couples an outlet of the first aftertreatment component with an inlet of the second aftertreatment component; a second end cap at a second end, the second end cap defining a second fluid chamber that fluidly couples an outlet of the second aftertreatment component with an inlet of the third aftertreatment component; and a first bracket having a first mounting interface, wherein the first bracket joins the first aftertreatment component, the second aftertreatment component, and the third aftertreatment component at an axial position closer to the first end than to a center of the second axial extent; characterised by the first bracket defining a first cross-sectional shape sized so as to allow passage of the first aftertreatment component therethrough, a second cross-sectional shape sized so as to allow passage of the second aftertreatment component therethrough and a third cross-sectional shape sized so as to allow passage of the third aftertreatment component therethrough such that the first bracket encircles each of the first aftertreatment component, the second aftertreatment component and the third aftertreatment component. a first aftertreatment component having a first central axis and a first axial extent, a second aftertreatment component having a second central axis and a second axial extent, and a third aftertreatment component having a third central axis and a third axial extent; wherein the first, second, and third central axes are substantially parallel; wherein at least a portion of the second axial extent and the third axial extent are shared with the first axial extent; a first end cap at a first end, the first end cap defining a first fluid chamber that fluidly couples an outlet of the first aftertreatment component with an inlet of the second aftertreatment component; a second end cap at a second end, the second end cap defining a second fluid chamber that fluidly couples an outlet of the second aftertreatment component with an inlet of the third aftertreatment component; and a first bracket having a first mounting interface, wherein the first bracket joins the first aftertreatment component, the second aftertreatment component, and the third aftertreatment component at an axial position closer to the first end than to a center of the second axial extent; characterised by the first bracket defining a first cross-sectional shape sized so as to allow passage of the first aftertreatment component therethrough, a second cross-sectional shape sized so as to allow passage of the second aftertreatment component therethrough and a third cross-sectional shape sized so as to allow passage of the third aftertreatment component therethrough such that the first bracket encircles each of the first aftertreatment component, the second aftertreatment component and the third aftertreatment component.