I upgraded my ‘03 to factory HID’s when I found them on fleaBay for a decent price ~5 years ago. They both had pretty advanced cloudiness in the lenses. In most cases, the cloudiness is the spray-on layer of UV protectant that came from the factory. I consider this a ‘sacrificial layer’ of protection, and the UV degrades it over time but saves the polycarbonate lens itself from the damage.
This layer can be sanded (or flaked) off pretty easily, then compounded and buffed. However, you MUST add the layer of protection back! I recommend a 2K clear coat rattlecan. It comes with the activator built right into the spray can, so it’s very simple. With the right surface prep and spray pattern, it’ll look like it just rolled out of Wixom.