Will the diffuser interfere with the trunk seal or weatherstripping?

The two-piece design sits at the rear bumper line and does not extend into the trunk area. Before final tightening, close your trunk fully to confirm clearance with your existing seal. Minor gaps at the edges are normal and do not affect weatherproofing.

Do I need to modify the bumper to install these, or is it adhesive-based?

These are designed as bolt-on additions that mount to your existing rear bumper attachment points. You'll use the factory mounting locations — no drilling or permanent adhesive required. Verify your bumper's fastener access points before ordering to ensure alignment with the diffuser mounting tabs.

Will these stay stable at highway speeds?

When properly secured to the bumper through all mounting points, the rigid FRP construction and dual-piece design work together to manage airflow. Do not skip fasteners or rely on partial mounting. Inspect all connection points after your first 100 miles and retighten as needed.