The HID ballasts determine the bulb power, 35W versus 55W. The factory ballasts are 35W, so for a 55W bulb, you would need to change the ballasts too. I upgraded the Q3 HID lights by installing a higher brightness HID bulb, the 35W Philips D3S "X-tremeVision Plus" part number 42403XV2C1, which offer about 1.5 times the light output (lumens) of a standard D3S bulb. These have a pretty standard 'Color Temperature" of 4800K...these are not the bluish/purple-ish bulbs. These bulbs just replace your originals. Make sure you get genuine Philips bulbs...there are lots of knock-offs being sold. I bought from HIDconcept.com, they appear to be genuine. They cost about $75 each. Note that these higher output bulbs will have a shorter life than the standard bulb.