Will this scrape on inclines or driveway ramps?

The diffuser sits beneath the rear bumper line and adds minimal extension. Test your approach angle on your own driveway before committing to installation; aggressive lowering setups increase scrape risk more than the diffuser itself.

Is this functional downforce or purely cosmetic?

This is a functional diffuser profile designed to reduce rear lift at highway speeds. Real aerodynamic benefit emerges above 60 mph; below that threshold, the visual impact dominates.

What surface prep is needed before installation?

Sand and clean the mounting surface on your bumper to remove dirt and old sealant. Verify mounting hole alignment with your bumper before drilling; reference your OEM service documentation for exact fastener locations if needed.