13/46 for close to 10,000 miles now. With a Renthal 46 Rear. It's just now
starting to get some scallop visible in it.
Chain/sprocket life all depends on the care you put into it.
Yes, a gearing change will help. Getting rid of the EXUP and opening up
the airbox and adding a fuel programmer will help as well.
Let that baby breathe and you'll see a difference.