I'd say the fastest is the one with the most power mods shortly before the engine explodes and logic would dictate it wouldn't be a Fazer 600 rather than a thou
But speed is nothing without control and I'd say that Lorenzo or Rossi are the fastest on any colour Fazer
As a weak second opinion I can tell you that Gold W reg ones with dented fuel tanks are not the fastest, even though the engine and gear box are, from all accounts, quite sweet for a 6,000 miler.
Meh. Time to change my trailer.