You'll be fine.
Standard D1S bulbs regardless of color temperature rating only draws 35W of power after they've been turned on. HIDs require ~35,000V of power to initially turn the bulbs on. After that it draws only 35W(less than a standard halogen bulb) to keep the bulbs on. The heat generated by an HID bulb is also less than that of a halogen bulb.
Vehicles that come with factory HIDs already have the electrical wiring and harnesses capable of handling that initial power at bulb start up. Bulb start up is where much of the issues occur because of the amount of power required to ignite the bulbs. Issues of melting the harness only arises if the power exceeds the handling capabilities of the wiring/harness. Some of the HID projector retro fitters out there are running higher wattage 55W HID bulbs, but this requires a larger ballast and stronger harness, but this is another issue altogether.
So you'll have no problem running 8000K D1S bulbs. However, just keep in mind the higher in temperature color you go, the less light output you'll get. There's a reason why factory equipped HIDs only come in 4,100K color rating. It gives the greatest amount of lumens(amount of light outputed by the bulbs).
