[John W]

The light patern is determined by the depth of the bulb mounting into the reflector. The low beam lights are called a 'projector' style, which are notoriously bad for light output when compared to a normal dicroic reflector.

I have fitted several HID kits to cars, and also installed a set on my ST4S.
As long as the HID bulbs are mounted at the correct depth the light still remains correctly focused. This is generally the difference between a good kit and a bad kit, as they all seem to use the same range of ignitors.

I buy all my kits from Autolamps-online.com, who will offer members a discount if you give them an email and mention 'DSC', or my name (John Webster).

They do a mounting kit specifically for the ducatis.

Because the 916/996/998 has seperate bulbs for high & low beam, you need a pair of kits (one is H1, the other is H3).

Cheers,
John.