Ive just bought some ultra-brite LED side light bulbs from a motorist shop in Hull (where I live), theyre a lot brighter than standard bulbs, and when the headlights are on theres a really good blue tint to the lights.
You can buy these online at www.speeding.co.uk for about £15 a pair, but if you buy them from the shop they cost £12.99
P.S. theyre also used for inicators, available in different colours.