so, im in my beginning phase of dabbling with HID lights now and am already considering doing one of those sanmak mods. what i've read so far is that overdriving a 55W bulb with the 100W ballast would produce better throw than using a 100W bulb, because of the smaller 55W bulb (and arc length?). what i don't get is how exactly is a bulb rated only for so and so power level and how exactly do we explain "overdriving an HID bulb". what is the difference in the components or make between a 55W and 100W bulb that makes them best suited for that power level?