Will this scrape on driveways or steep inclines?

Rear diffusers sit lower than the main bumper line. Inspect ground clearance at your typical approach angles before installation. Carbon fiber won't crack from light contact like plastic, but avoid repeated scrapes to preserve the finish.

Does this add functional downforce or is it cosmetic?

The Sceptre design is styled for visual impact. Any aerodynamic effect at street speeds is minimal. Install it because you like the look—don't expect measurable performance gains on the road.

What finish should I use on uncoated carbon?

Sand the surface lightly with fine-grit paper, then apply your choice of clear coat or paint. UV-protective clear coat is recommended to prevent the resin from oxidizing and yellowing over time.