Will this diffuser scrape on driveways or steep inclines?

The GMX profile extends lower than OEM bumper covers. Check ground clearance at your typical approach angles before installation. Measure your current ride height and compare to the diffuser's leading edge; adjust your expectations for parking lots and steep entries accordingly.

Does this diffuser provide functional downforce or is it purely cosmetic?

This is a styling diffuser designed to enhance the visual aggression of the rear bumper. While the blade lines are proportioned for airflow aesthetics, real aerodynamic benefit depends on speed, vehicle geometry, and overall rear wing or wing-less configuration. Install it for looks first; any downforce gain is secondary.

What prep and finish should I apply before installing?

Raw carbon fiber benefits from UV-protective clear coat to prevent oxidation and fading. Sand the surface lightly and apply your chosen automotive clear coat before bolting it down. This step protects the weave and keeps the finish consistent with your paint scheme over time.