Do the LEDs come wired and ready to plug in?

LED wiring configuration is not specified—get with your installer before ordering to confirm how the harness connects to your Mustang's electrical system. Most shops can adapt the connector if needed.

Will I need any additional fasteners beyond what mounts to the factory points?

The grille assembly mounts at factory anchor locations. Additional hardware like brackets, clips, or trim fasteners are not confirmed in the package—check the install documentation once it arrives or contact the shop doing the work to verify what they'll need on hand.

Does this arrive ready to install, or does it need prep work?

It ships with a gloss black finish. If you're planning a different color or final coat, plan for light surface prep before paint—your installer will handle that as part of their process.