In '88 Wittner's race bike engine was nothing to do with either production or QA. The original engine supplied to Wittner was a tired development prototype because with engineering resources being limited at Mandello, Todero didn't want to give away an unworn unit. This was about 5 years before the engine was in production. Eventually Todero and Wittner got together and the Daytona was the result.
Finding the right alloy to use for the heads was a major reason it took until '93 to get the Daytona engine into production. The highly temperature resistant alloy used in '93-on production was difficult to cast, and as a result the occasional casting flaw snuck through, which was a QA issue. Most were fine but I saw one come off a near new Centauro once, in two pieces
After Piaggio took over and decided to continue with Aprilia's Griso development, basically an update to the Centauro concept, they looked at the existing 8V engine and decided to move the cam drive to the back of the head so air flow could cool them better. That necessitated chains instead of belts because space was limited behind the heads. It took a while to complete, so the first year (2007) Griso was produced with the two valve per cylinder engine.
