Will this interfere with my trunk seal or lower bodywork?

No. This lip is designed as an air dam under the bumper, not an extension that reaches rearward. Verify clearance with your specific setup, especially if you've lowered the suspension or added suspension components that alter ride height.

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

This lip is engineered to work with DL-R bumper mounting points. Use hardware that secures it to your bumper cover per the DL-R system—drilling into the bumper itself is not necessary. Your DL-R cover documentation will specify the correct fastening method.

Is this stable at highway speed, or will it generate lift?

Front lips are designed to reduce underflow turbulence and add visual depth, not to generate downforce. At highway speeds, FRP construction remains stable when mounted securely to the bumper. Ensure all fasteners are tight and torqued per your vehicle's service manual before extended driving.