Will this diffuser scrape on steep inclines or driveways?

The diffuser extends below the factory rear bumper, so low approach angles or aggressive driveway slopes may cause contact depending on your suspension setup and load. Inspect clearance with your vehicle at normal ride height before final fitment. Adjust mounting height slightly if needed to suit your typical driving conditions.

Is this functional downforce or purely cosmetic?

This diffuser is both. The profile generates genuine downforce by managing airflow under the rear of the vehicle, improving stability at speed. It also delivers the aggressive aesthetic of a track-focused design, so you're getting real aerodynamic benefit alongside the visual presence.

Does this come with mounting hardware?

The three-piece assembly is included. Review your vehicle's rear bumper attachment points and OEM fastener locations before installation to confirm you have the correct hardware for your setup. Most installations use factory bolt holes.