Real engine and sound effects,neutral engine revving if possible,Tied to the sound card and the smoker device,also haveconsideredusing the new smoker to simulate a kill situation where the smoker kicks into high fan power and fills the tanks with smokeemittingfrom hatches or other open to air parts of the tanks like engine grills,I mean the new units will pump out some smoke and what could be more real and easier on the battle field to see than a tank engulfed in smoke?Sax