Oh, yes, if you are not a DD devotee, they sound WAYYY different from conventional 4-stroke Diesels. The Roots blower is an integral part of the engine, and has a distinctive and high sound. The engine is running twice as many power strokes as a 4-stroke, and thus sounds twice as fast. So, full power at near rated RPM sounds to the unexperienced to be an engine well into a runaway when it is just running fine. (Your neighbors are just going to LOVE you.....)
Jon