Will this scrape on steep driveway approaches or parking lot angles?

The diffuser extends from the factory rear bumper area, so scrape risk depends on your approach angle and current ground clearance. Test fit before committing to permanent mounting. If clearance is tight, you can adjust mounting depth slightly or limit the installation to level surfaces only.

What hardware do I need to bolt this on?

The diffuser assembly ships without fasteners. You'll need to source bolts compatible with your factory rear bumper mounting points—check your Mustang service manual or test-fit to confirm bolt size and quantity before ordering.

Is this functional downforce or purely cosmetic?

This is a visual accent piece. At street speeds, aerodynamic effect is minimal. It's designed to add rear-end character and visual balance to the fascia, not for track performance gains.