The present disclosure relates to an engine system comprising an ICE; an exhaust system; and an engine control unit for controlling operation of the engine system between at least a first operating state resulting in a first exhaust temperature range, and a second operating state resulting in a second, higher, exhaust temperature range. The exhaust system comprises a low frequency sound attenuation portion including a first tubing section having a first flow area; a second tubing section, having a second flow area smaller than the first flow area; and a third tubing section having a third flow area greater than the second flow area. The low frequency sound attenuation portion is dimensioned to achieve laminar flow through the third tubing section when the engine system is in the first operating state; and turbulent flow through the third tubing section when the engine system is in the second operating state.