Will this interfere with the trunk seal or liftgate?

The rear lip is designed to sit flush with the existing bumper line. Before installation, verify clearance between the spoiler and your trunk when fully closed. If your vehicle has factory weatherstripping, check that the lip doesn't compress or pinch the seal — minor trimming of stripping may be needed for a clean fit.

Can I install this with adhesive, or do I need to drill?

This diffuser uses factory mounting points, which typically accept bolts through existing holes in the bumper. Adhesive alone is not recommended for rear lip stability at speed. Use mechanical fasteners aligned with OEM locations to ensure the part stays secure during highway driving.

How should I prep and finish the FRP?

Sand the entire surface with appropriate grit to create adhesion for paint or clear coat. After sanding, wash and dry thoroughly, then apply your chosen primer and topcoat system. FRP accepts standard automotive paint finishes — follow your paint manufacturer's guidelines for surface prep and cure times.