Sadly it seems that D5S is the entry level Xenon bulb and not many manufacturers make it besides Phillips. They may make a better bulb in the range but I suspect not.
It seems D5S is a low wattage Xenon combi (driver, ballast and bulb in one) so I doubt you would swap up without having to ensure the wiring loom can supply a more substantial feed - if indeed that was possible.
If you have a local specialist nearby or a local auto electrician you could have a chat to see what your options are, bearing in mind any changes might then cause warranty issues.
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