when buying after market xenon halogen bulbs or HID you have to look for their light temperature. Best temperature for most light is between 4500K and 6000K. Silverstars are rated at 4000K. Other brands have a higher temp. 6000K is very white, 8000K is blueish, 10000K is purpleish, and 12000K is pinkish.
Not all halogen lights will advertise their color, but some will. PIAA's are over rated. I ordered fromt his website
http://www.eurodezigns.com/ the bulbs I got from them was 8500K and I liked them, but eventually upgraded to HID.