An exhaust component comprises a main casing and at least one partial casing pressed against the main casing. In a developed state, the partial casing has an elongated shape along a longitudinal line and is defined along a transverse direction, substantially perpendicular to the longitudinal line, by two side edges opposite one another. The partial casing has a given developed longitudinal length. The partial casing has no fastening to the main casing on at least one longitudinal segment, and the longitudinal segment extends from one side edge to the other and extends in total over a cumulative developed longitudinal length of at least 20% of the given developed longitudinal length.