I purchased a pair of the Sylvania Silver Star H4 headlamps and installed them this morning. Having removed the front leg shield from the scooter before, I am familiar with how the headlights are wired in so I was able to just reach up around the front fork to behind the headlights and feel my way through it. Took 5 minutes total to disconnect the existing lamps, remove the two protective rubber boots, undo the spring tensioner behind each headlight, remove the old headlight, and repeat the process in reverse to install the new headlamps. Be sure to take care not to touch the glass headlamp when inserting, is reported to shorten the life of the bulbs as the oil from your finger skin boils on the hot bulb.
The only thing I had to do that wasn't stock -- on each of the new H4 bulbs there are two little metal prongs/tabs which project out around a rectangular opening at the bottom part of the metal bulb housing -- the Sylvania's don't have the same sized hole as the stock bulbs, so they don't really fit that well out of the packaging - I had to bend the two little prongs flat on each of the bulbs before installing them, and then they fit like a glove. There are three ears/tabs around the edge which do a great job of "keying" the bulbs into the sockets and the spring tensioner clip which clips in behind each bulb does a great job of holding them in place.
The difference is awesome. The light is whiter and way brighter. Can't wait to try them tonight to see how much more light is thrown at the street and surroundings. Easy upgrade, appears to be a lot more light for the money.
For a better idea of what I'm talking about when I noted having to bend down the two little metal tabs on the new headlamps to make them fit, check out my photo gallery:
http://burgmanusa.com/gallery/Nakes-Burgman-400