An exhaust system for use with a combustion engine is disclosed. The exhaust system may have an exhaust passage, a reduction catalyst disposed within the exhaust passage, and an injection device configured to inject reductant into the exhaust passage upstream of the reduction catalyst. The exhaust system may also have a dosing channel forming a portion of the exhaust passage. The dosing channel may have a thermal conductivity different than adjacent upstream and downstream portions of the exhaust passage and extend a distance upstream of the injection device sufficient to transfer enough heat to an extension of the dosing channel downstream of the injection device to cause vaporization of reductant that impinges on the downstream extension.