Will this diffuser scrape on steep inclines or driveways?

The blade profile is designed to sit just below the factory bumper line. Check your vehicle's loaded ride height and existing rear bumper clearance — if your stock setup clears driveways without scraping, this diffuser should perform the same way. Test your steepest approach angle before paint to confirm.

Is this functional downforce or cosmetic only?

The blade profile is cosmetic. It follows the factory rear bumper shape to complement your styling without adding aerodynamic function. Pair it with other rear aero if you're building a fully tuned setup.

What fastening method should I use?

The diffuser is engineered to align with factory rear bumper mounting points. Confirm your bumper hardware locations before assembly and use fasteners appropriate to your installation method — reference your vehicle's service manual or test-fit with temporary hardware first to lock positioning before final fastening.