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

This lip mounts to the underside of the bumper and does not extend into the trunk area. Verify clearance between the diffuser edge and your vehicle's lower bumper body line before drilling or clamping attachment points.

Should I use adhesive or drill through to mount this?

Both methods work. Adhesive offers a clean install with no holes; drilling provides a permanent mechanical bond. Ensure the mounting surface is clean and dry, and allow adequate cure time if using adhesive. Reference your vehicle's OEM bumper reinforcement layout to avoid drilling into structural components.

Will this affect high-speed stability or cause lift?

A rear diffuser improves underbody flow and can reduce lift at speed. This design is styled for visual impact and mild aerodynamic benefit on street applications. For track use, monitor rear-end behavior during your first few sessions to confirm it works with your suspension and driving style.