This site will give you the figures
http://www.gearingcommander.com/I ride mostly on the highway and with 15:41 was always looking for another gear when in top
Went to 15:39 and this transformed the whole highway riding experience, lowered the RPM by about 500, put the motor into a real sweet spot at 120 kph ( speedo on mine reads about 10% high )
Downside is need to slip the clutch in 1st a leetle bit more, not a worry tho for me