Carbon fiber would suck as a mudflab as it has no flex. Think about what it does, then how it would suck as that use.
That said, I have some ideas as well for some accent pieces. I am trying to stick with a blue highlights with black background for my Sonic Yellow wagon. I have thought about trying to cf wrap the plastic on the mirror with the blue/black cf weave. A nice wrap of the interior pieces, maybe a vent cowl wrap. pillar covers, etc.