Most people on the board will reccomend you pick up Sylvania's Silverstar signal lights. They are a bluish tint when off, and when on, the bulbs light up amber; keeping them DOT approved and legal.
However, if you dont want to go with the slick blue look or dont want to pay the ~$25 for two signal bulbs, you can always paint your amber bulbs silver, and just leave a couple slits unpainted. The Solaris Invisibulbs are just normal bulbs painted...
If you get the Silverstars, I reccomend ordering them from Sylvania's website; I spent half a day looking for the ones for my bimmer and no one had the right bulb set