I decided my white Defi gauges looked horrible in contrast to the rest of the green WRX interior backlighting. I colored the controller and the gauges with transparent glass paint. Its a pretty easy process, it just requires the confidence to tear into these pricey gauges. I did a video tutorial and I got my original information from the thread linked at the bottom.
My YouTube Tutorial:
Part 1: Disassembly and coloring
Part 2: Reassembly and glory
Original tutorial I read:
S2KI - S2000 Forums -> Changing Defi BF gauge color in easy 9 steps- the cheap way