A systematic and practical approach to noise reduction is described as applied to a 200kW heavy duty truck engine. The project described covered an initial detailed assessment of the noise and vibration characteristics including running engine tests and experimental modal analysis. The components identified as major noise sources were re-designed with due regard to practicality and ease of production. The techniques used to achieve a 95 dBA noise target (at 1m and rated conditions) with minimum shielding are described. A 93 dBA version is also described in which additional shielding was incorporated. These new noise levels represent reductions of approximately 4 dB and 6 dB respectively from the baseline engine.