Check this page out.. Says something about FIAT Abarth.. But im not reading it so here is the article.
https://www.fazaabarth.info/exhaust.htm
Below from this page.
https://www.dannatavintage.com/2019/02/18/carlo-abarth-2/
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Carlo Abarth – il suo dodici cilindri.
He wanted to compete in the Marche World Championship, against cars like the Ferraris and the Porsche, to name the most famous and victorious, but his desire, ambition, was sedated in the bud.
A big disappointment for Carlo Abarth
Then, the CSI (International Sports Commission), decided to bring the displacement limit to 3000 cc for the prototypes, forcing it to abandon the project.
After having spent a lot of time and money, and having a car ready to run.