The VFR is rather over geared and as such reaches top speed long before the redline. i.e. it is power limited rather than rev limited. There is a good deal of latitude to play with but a one seventeenth change in final drive gearing produces more torque and doesn't sacrifice and top speed. The thing that is sacrificed (to a small extent) is fuel economy. The OEM standard front sprocket on a Fi has 17 teeth or 16 on the Vtec. An aftermarket 16 tooth sprocket for your Fi should cost you around £10 including delivery in the UK.
So, How do you do it?
First, make sure that you have the necessary tools available in addition to the OEM tool kit that Mr. Honda supplied. You don't need anything fancy but the picture below shows the minimum kit that I would recommend you have before starting.
The small torque wrench is needed for tightening the sprocket bolt and the large one is necessary for re-tightening the rear wheel bearing clamp after you have adjusted the chain.
Undo the two main fairing fixing bolts to allow the fairing to move freely and remove any crash bobbin (frame slider) that you may have fitted. The job is made easier if the left lower fairing is removed completely, but it is fairly easy with it in place.
Undo the four 8mm bolts (marked in the picture below) that hold the aluminum cover over the sprocket.
Lift off the cover but be careful not to stress the hydraulic clutch hoses or the speed sensor cable.
Now you can simply undo the sprocket retaining bolt and slide the sprocket from the gearbox output pinion. This is a great time to clean out all the old chain lube that has collected inside the cover and surrounding area.
Replace the 17 tooth OEM sprocket with the new aftermarket 16 tooth one. Note that an aftermarket sprocket will not have the rubber pads on either side. These are intended to quieten the chain drive, but I cannot hear any difference in noise level between the two types of sprocket.
Torque the sprocket retaining bolt to the recommended setting. (51Nm)
Now all that is left is to re-fit the cover.
NOTE. When re-fitting the cover make VERY sure that the speed sensor coupling has properly engaged over the sprocket bolt head. If it is not seated properly, there could be damage to the speed sensor coupling (the cream cylinder in the above photo) when the cover is tightened down. Speed sensors cost about £100 from Honda, so it is worth making absolutely sure. You can rotate the sprocket (by turning the rear wheel) while carefully re-locating the cover. You should be able to push the cover home without any force.
And finally DON'T FORGET TO ADJUST THE CHAIN!! If the bike feels like it has more vibration than before, slacken the chain slightly and try again. It is a common mistake to over tighten the chain and it isn't easy to get it just right first time on the VFR
Job Done!
Now get out there and enjoy the extra torque. It'll be very useful for those wheelie kings among you!