Ok stay with me here as I'm not sure I can explain this well.
So on the concept, it looks almost like the afterburner light is coming from behind the actual brake light bulb. That's what creates that look. What I'm thinking could be done is using the AACStyle CCFL lights and placing some sort of plastic shielding around the light that obscures it so the light can only be reflected out and forward causing the effect. Think of a Bic pen where the inner ink portion is the CCFL. Cut about a quarter of the outer plastic off, bend the whole thing into a semi circle and place it in the light housing. This way, you can't see the actual CCFL but you can see the light coming out around the plastic housing. I think this would create the exact afterburner effect we are all looking for.
I can try and explain better if needed. I''l try and draw up a picture to post as well to clarify.