Will this lip interfere with the trunk seal or bumper trim?

No. Front lips are mounted to the lower bumper fascia and do not contact the trunk. Verify your bumper's existing hardware locations before drilling to ensure clean alignment with the lip mounting points.

Should I use adhesive or drill through the bumper to install this?

Both methods work. Adhesive offers a cleaner look if your bumper is in good condition; drilling provides permanent security if you prefer mechanical fasteners. Choose based on your bumper's finish and your long-term plans for the vehicle. Sand and prep the mounting surface thoroughly either way.

How stable is an FRP lip at highway speeds?

FRP is rigid and lightweight, holding its shape under normal driving conditions. Ensure mounting is secure and level before driving at speed. Inspect fasteners or adhesive periodically, especially after 500+ miles, to confirm the panel remains seated.