An internal combustion engine includes a cylinder receiving air during operation through an intake air fluid passage, an engine component that at least partially forms a section of the intake air fluid passage, and a gas diffuser having a tip disposed within the intake air fluid passage. A gas injector housing is connected to the body portion of the gas diffuser. The gas diffuser is structurally interchangeable with other gas diffusers such that gas dispersion in various engine applications can be modified by installing an appropriate gas diffuser and otherwise maintaining common engine parts.