Will this diffuser scrape on steep driveways or inclines?

The shark-tooth profile extends below the bumper line, so angle and driveway approach matter. Measure the lowest point of your current bumper, then verify ground clearance before installation. If you frequently approach steep angles, test the fitment at a slow speed first to confirm your setup.

Is this purely cosmetic or does it have functional downforce properties?

This is a cosmetic diffuser. It creates visual aggression and shadow lines typical of shark-tooth styling. Functional downforce requires specific aerodynamic shaping and is not the purpose of this design—focus on the look it brings to your rear end.

What prep and finish should I use before final paint?

Sand and prep the primer surface with your chosen sandpaper grit before applying primer, sealer, or topcoat. FRP accepts standard automotive primers and paints well. If you're unsure about your specific paint system, consult your paint supplier to ensure compatibility with plastic substrates.