[1speedbike]

It wouldn't hurt, but it might be overkill. You might end up paying close to what you paid for the spoiler just to add more clearcoat, when you could have bought a "better" brand than AutoCarbon with that money and not had to worry :P

If they claim that it's clearcoated already, personally, I would just wax it regularly with a UV-protectant wax. If you don't already use a UV-protectant wax, Mothers Synwax and Einszett Glanz Hart Glanz wax are both UV protectant and I've been using either one or the other on my carbon parts (regardless of what I wax the rest of the car with). Einszett is a little more "upscale" and it's from Germany, so I've been just waxing the whole car with it recently and it seems to last longer. As far as I know, regular Carnauba wax doesn't offer any actual UV protection, just protection for the clear coat which itself has the UV blocking built in. Only some synthetic or synthetic/carnauba mixes seem to have it added in.