Do these use the factory wiring harness, or do I need new connectors?

These come pre-wired with a harness. You'll tap into your vehicle's existing fog light circuit—no new connectors required if your Mustang already has fog light wiring in place. If wiring doesn't exist, you'll need to run a separate circuit from your battery through a relay.

Will I need to remove the bumper to install these?

No. These mount directly at the factory fog light apertures. You'll access them from underneath without full bumper removal—basic hand tools and about 30 minutes total.

Are bulbs included in this package?

Bulbs are not included. You'll need to source 899 bulbs separately—they're cheap and available everywhere. Pick whichever brightness and color temperature you prefer.