Will the clear coat yellow over time in direct sunlight?

The factory-applied UV-protective clear coat resists yellowing far better than uncoated carbon fiber. Over time, any clear coat can dull slightly with weathering — consider a UV-resistant wax or sealant applied annually to maintain shine and add an extra barrier against sun exposure.

Do I need to seal the edges where the two pieces meet?

The seams where the two fenders meet should be sealed with clear silicone or edge-seal tape to prevent moisture and debris from entering the joint. This is standard practice and protects the carbon weave underneath at stress points.

How much lighter are these compared to factory fenders?

Carbon fiber is significantly lighter than factory steel, reducing unsprung weight at each corner. The exact weight difference depends on your vehicle's original panel thickness, but the reduction is substantial enough to benefit handling and fuel economy over a full set.