Do these bolt straight to the factory holes?

Yes. These mirrors mount at the factory rocker points — no drilling or bracket modification needed. Bolt them up and wire in the power connector.

Will the heated element work in extreme cold?

Heating elements respond fastest in moderate cold and wet conditions. In sustained sub-zero temperatures, allow a few extra minutes for the defrost cycle to clear heavy ice buildup.

Do I need a relay or new wiring harness?

Wiring specs are not confirmed — consult your vehicle's service manual or have an installer verify the harness configuration before running power to the mirrors.