Exhaust sys

Jacques, i think there are several muffler systems that would be seen as production original on the Miura series. They all mount on the header pipes in similar fashion. The earliest systems had small mufflers usually round cans, but in later (early cars) these cans could be oval.  Usually had the cone section expansion chambers.
As time progressed, i guess ANSA became more sophisticated in production, Miura owners wanted a little more quiet, so the mufflers became slash cut style to fill all available space and became larger as well. I am guessing to avoid the cost of the custom cone sections, the units were fitted with the round end flares, also wrinkle black paint, red inside pipes is seen on replacement systems sold at a dealer. here is a drawing and picture of the earliest system type and the last SV style.

the later systems , altho attractive, have a serious mismatch problem with tail pipe to tail pipe, leading to Louisiana blackened Cajun rear ends.