[shorod]

For this application I don't really think you'll have an issue. There could be a bit of extra "noise" due to the distance between the battery and the tap, but for an HID system it shouldn't be a problem. The HID system uses ballasts that step the voltage up significantly but shouldn't effect longevity of the bulbs.

The battery of the car essentially acts as a large capacitor to filter noise from the alternator (which produces somewhat noisy rectified AC) as well as current surges, and ideally you want your load tied as close to it as possible to minimize spikes and noise. But I can't really think of a practical application where the surge would be significant enough to cause damage to the end product. I'd expect if a product were damaged by the surge from the starter, it probably was not properly designed for application in an automobile.

-Rod