John Dickie's book 'Mafia Republic' has an account of a bugged meeting between Violi and a Sicilian mafioso where they disagreed (without rancour) about the rules of inductions into the Mafia. The Sicilian wanted a made guy in Sicily to be able to move to the USA and immediately assume made status, whereas Violi wanted there to be a five year wait between a 'zip' moving to the US/Canada and assuming made status there.

Dickie speculates that Violi's insistence on this cooling-off period lead to his death as putting this in place would have hindered the heroin trafficking of the Pizza Connection at that time.

I don't have the book to hand so I can't recall who the Sicilian that Violi met was. It's a great book btw.