i went with a did heavy duty gold chain, 15t front and 42t rear, that way you get even chain and sprocket wear, the bike much more lively, i didn't notice any difference in fuel costs, my speedo is out, when it reads 30 i'm only doing 23/34mph. the only downside i can see is when doing long motorway trips at high speed, in excess of 120mph, the bike feels like it could do with an extra gear, but as i use my bike for fun and i rarely go near a motorway, i don't care. you can always try some different sprockets and if you don't like them, sell them on and go back to standard...
