Will this diffuser scrape on speed bumps or driveway inclines?

Depends on your suspension setup and approach angle. Dry-fit and measure your ride height before committing to install—a slight drop in suspension will increase scrape risk. Test at your typical parking and driving speeds on your own property first.

Is this functional downforce or pure cosmetics?

This is styling-focused. It follows GT500 aesthetics and channels air at the rear, but don't expect measurable aero gains at street speeds. If you're after true downforce, pair this with a front splitter and underbody pan for a complete system.

What prep work does the diffuser need before paint?

Sand the primer surface with medium-grit sandpaper and wipe clean before applying your base coat and clear. FRP absorbs moisture—let it cure fully if you've stored it outside, then sand and dry again before any adhesive or fastener installation.