LED bulbs are pure red, and stay red. There is no coloring that would fade, the LEDs emit the colored light. Drawbacks to them are you get a "dot effect" because the light is very directional from LEDs, and only goes straight through the lens, the reflector in the taillight is useless. Also, you'll need to switch to a "variable load" flasher... so you do not have the ghetto fast-flash turn signals.

Another option is colored gel bulb covers. They are a translucent, colored cap that slides over the glass of the bulb and changes the color. They dont fade and have a very rich color. They are about $1.50, ive only found them at autozone so far.