Will this scrape on steep driveways or inclines?

Diffusers sit within the rear bumper profile and do not extend below the factory bumper line. Check your vehicle's current approach angle — if the OEM bumper clears, this diffuser will too.

Does this add downforce, or is it purely cosmetic?

This is a styling piece. It mimics the L Sport look without aero ducting or splitter geometry. Performance benefits come from the weight savings of carbon fiber over plastic, not from downforce generation.

What finish should I apply to the carbon?

Carbon fiber can be left raw to show the weave, or sealed with clear coat for UV protection and easier cleaning. Sand the surface lightly and apply your chosen finish — gloss, satin, or matte all work. Most builders recommend clear coat to preserve the material long-term.