Will these lips interfere with my trunk or door seal?

These are front under-spoiler pieces designed for the lower bumper area, so trunk and door seal interference is not a concern. Verify clearance between your front bumper bottom edge and the ground before installation to ensure proper fitment on your specific vehicle.

Should I glue these on or drill mounting holes?

FRP lips can be mounted either way depending on your preference and vehicle setup. Adhesive-only mounting keeps the bumper clean and reversible; drill-through fastening provides permanent security. Choose based on whether you want the option to remove them later.

Will the FRP stay stable at highway speeds?

FRP is rigid enough for highway use when properly mounted and secured. Ensure both left and right pieces are equally supported and fastened to prevent vibration. Sand and prepare the mounting surface for optimal adhesion if gluing, or use fasteners rated for plastic if drilling.