Gentlemen: I also use on my Sirio/Collari the Nova Rossi number 6 (medium) turbo plug with good results.

For break in, I use the method described by Andrea and it works very well. What I do is after each a tank I usually close the needle 1/8 of a turn. Do this after you have done a tank or two at WOT in a very rich setting. In total, I give about 10 tanks of break in: 2 at WOT Rich, around 5 at WOT closing the needle little by little (1/8 of a turn) after each tank and after that I turn the needles to factory settings. and work my way up from there for full power settings.