I fitted a 14 tooth front sprocket last year and haven't bothered swapping back to the 15 as standard. This gearing really suits me and acceleration up to an indicated 90mph (GPS) is quite rapid. Went out tonight for a spin and made a conscious attempt to see how the seedo compares to the GPS and the difference is very close to 10mph at 60mph. This means that at an indicated 60mph on the bikes speedo I am actually travelling at 50mph.
Makes trail riding easier as you can use 2nd gear a bit more and 50mph on the bikes' speedo in top gear is 3000rpm, just nice for decent acceleration without shifting down.
Hope this helps.
