VW AD motor sound

Old VW Air-cooled flat 4 1600cc OHV "AD" motor combustion noise gives me the most pleasant feeling of satisfaction that is very similar with that of Strings of orchestra. The sound is perceived as a comfortable vibration rather than simply some noise, and it is also an indispensable stimulation to be supplied on my Semicircular canals through Cerebellum. And this stimulating sound must be discerned periodically without end, because this is the true reason for me to live my own life.
Combustion noise here I say is completely different from some louder exhaust noise, I dare say, the sound from valve overlapping so to speak that of Original inspiration. The most favorable note is heard when the best balancing is established with the load.