One thing I really like on a bike is other people knowing when I am braking so I like to fit additional light and recently I have discovered brake light modulators and this was my first job on my FZ.
I have bikevis bullet V2 LED's, £32 for two red and two white, and a small flasher unit, there are many many types available for around £30.
I only remembered to take pictures when it was back together, sorry.
It is a relatively simple job.
Remove the whole rear end.
Take out the light, measure and drill holes for the cables.
Line them up and stick them in place.
Rebuild the rear end, dismantle rear end and fit the flasher unit, rebuild the rear end again.
Refit the rear end.
Run the cables through and join as per instructions.
Check you have it right and it should look like the video below.
I prefer to have the light spread as far apart as possible but the rear of the FZ1 is quite tight so I had to have the new ones on the light unit but the effect is OK.
http://youtu.be/JsxLjkmm5m4