The Bertocchi name is used by this shop in Yokohama (Miracolare) that does parts for Italian cars, including Maserati's. They seem to have copyrighted to use it across their exhaust offering (Lambo, Ferrari, Maserati and Alfa Romeo).
as far as I know, they are not available in the US as the shop making and installing them is fairly small. The whole set, with silencer (for idling). costs JPY 720,000 (sport cats, middle section, back box). Quite expensive.