An after-treatment system for use with an engine, the engine having an exhaust conduit, the exhaust conduit adapted to route a flow of exhaust gas from the engine during operation of the engine, the after-treatment system being adapted for connection to the exhaust conduit and disposed to receive and treat the flow of exhaust gas from the engine, the after-treatment system comprising: a diesel oxidation catalyst, DOC, connected to the exhaust conduit and arranged to receive the flow of exhaust gas from the engine; a transfer conduit connected in a downstream end of the DOC; a diesel exhaust fluid, DEF, delivery device associated with the transfer conduit and adapted to selectively inject DEF into the transfer conduit to be carried in a downstream direction by gas passing through the transfer conduit during operation of the engine; and a series-compact device, comprising: a soot-reducing device comprising a substrate and being connected to a downstream end of the transfer conduit, the soot-reducing device being arranged to receive the gas passing through the transfer conduit during operation of the engine; and a combined selective catalytic reduction, SCR, plus ammonia oxidation, AMOx, catalyst, wherein the AMOx catalyst is formed as a coating on the SCR catalyst, the combined SCR/AMOx catalyst comprising a substrate being physically connected to a downstream end of the substrate of the soot-reducing device opposite the transfer conduit, the SCR catalyst being arranged to receive the gas passing through the soot-reducing device during operation of the engine; wherein the soot-reducing device is a diesel particulate filter, DPF, that is made from a monolithic, thin wall-flow type substrate, which is made from advanced cordierite, AC, or aluminum titanate, AT, and has an asymmetric channel, ACT, construction such that a size of inlet channels of the DPF is larger than a size of outlet channels of the DPF. a diesel oxidation catalyst, DOC, connected to the exhaust conduit and arranged to receive the flow of exhaust gas from the engine; a transfer conduit connected in a downstream end of the DOC; a diesel exhaust fluid, DEF, delivery device associated with the transfer conduit and adapted to selectively inject DEF into the transfer conduit to be carried in a downstream direction by gas passing through the transfer conduit during operation of the engine; and a series-compact device, comprising: a soot-reducing device comprising a substrate and being connected to a downstream end of the transfer conduit, the soot-reducing device being arranged to receive the gas passing through the transfer conduit during operation of the engine; and a combined selective catalytic reduction, SCR, plus ammonia oxidation, AMOx, catalyst, wherein the AMOx catalyst is formed as a coating on the SCR catalyst, the combined SCR/AMOx catalyst comprising a substrate being physically connected to a downstream end of the substrate of the soot-reducing device opposite the transfer conduit, the SCR catalyst being arranged to receive the gas passing through the soot-reducing device during operation of the engine; wherein the soot-reducing device is a diesel particulate filter, DPF, that is made from a monolithic, thin wall-flow type substrate, which is made from advanced cordierite, AC, or aluminum titanate, AT, and has an asymmetric channel, ACT, construction such that a size of inlet channels of the DPF is larger than a size of outlet channels of the DPF. a soot-reducing device comprising a substrate and being connected to a downstream end of the transfer conduit, the soot-reducing device being arranged to receive the gas passing through the transfer conduit during operation of the engine; and a combined selective catalytic reduction, SCR, plus ammonia oxidation, AMOx, catalyst, wherein the AMOx catalyst is formed as a coating on the SCR catalyst, the combined SCR/AMOx catalyst comprising a substrate being physically connected to a downstream end of the substrate of the soot-reducing device opposite the transfer conduit, the SCR catalyst being arranged to receive the gas passing through the soot-reducing device during operation of the engine; wherein the soot-reducing device is a diesel particulate filter, DPF, that is made from a monolithic, thin wall-flow type substrate, which is made from advanced cordierite, AC, or aluminum titanate, AT, and has an asymmetric channel, ACT, construction such that a size of inlet channels of the DPF is larger than a size of outlet channels of the DPF.