Will this wing stay stable at highway speed?

Yes. Carbon fiber's rigidity combined with the single-piece design resists flex under wind load. Ensure mounting bolts are torqued to your vehicle's service manual specs and check them after your first 100 miles of driving.

Does this interfere with the trunk lid or tonneau cover?

The Street Runner profile is designed for tailgate mounting without obstruction. If you run a tonneau cover or bed cover, verify clearance by measuring the cover's rear edge height against your tailgate and comparing it to the wing's mounting position on your specific vehicle setup.

What mounting hole pattern does this use?

This wing is engineered for standard tailgate mounting locations. Before final installation, locate your OEM tailgate bolt holes and confirm they align with the wing's mounting footprint. If your tailgate has been modified or repaired, drill new holes based on the wing's bolt pattern and refer to your service manual for fastener specifications.