Will this interfere with my trunk seal or rear bumper fitment?

No—this is a front lip. It mounts to the lower front bumper area and has no interaction with trunk, doors, or rear body panels. Fitment is isolated to the front end.

Does this require adhesive, or do I drill through the bumper?

This lip uses factory mounting points on the bumper cover—no adhesive, no drilling. Confirm your bumper's existing hole locations before assembly to ensure alignment with the mounting tabs on this panel.

How stable is this at highway speeds?

FRP air dams are designed to stay rigid at speed when properly secured to factory mounting points. Ensure fasteners are tightened evenly and check them after your first few driving sessions to confirm they remain tight. Periodic inspection will keep it stable for the life of the panel.