at Pebble Beach, the best of show award went to the 1924 Hispano-Suiza H6C Nieuport-Astra Torpedo with this unique exhaust.

You can see “Steigboy” branding, referring to Steigboy Apparatebau, a Leipzig-based outfit founded in 1921, that made vacuum exhaust systems

This is an early vacuum muffler, sometimes referred to as an ejector muffler. Those big, round hamburger-looking sections allow for a large expansion of volume right after the header. That sudden volume change is supposed to knock down the sharp pressure pulses before they exit. 

In other words, it’s a reactive silencer tuned by volume and geometry rather than the fibrous packing in modern exhausts.

According to German literature about the Vacuum-Auspuff from when this stuff was new, a beveled baffle inside sits opposite the outlet, and the outlet pipe has helical vanes. That’s supposed to swirl and accelerate the gas flow out of the neck, inducing a slight vacuum in the main chamber. The idea was to scavenge cylinders between pulses and cut back-pressure while still muffling.

https://www.thedrive.com/news/whats-up-with-the-weird-exhaust-on-pebble-beachs-best-of-show-car