Slave cylinder piston diameter?

Im contemplating fitting an Oberon clutch slave cylinder to my 1098 Streetfighter because of air getting into the line, affecting engaging neutral within a few days of bleeding (many reports that the Oberon performs more reliably).
Can anyone tell me what the standard Ducati slave cylinder piston diameter is on this bike, because I am a little concerned about reduced travel with the 29mm Oberon piston? Thanks