Do I need to drill into my door panels to install these?

No drilling required. These caps are designed to sit over your existing door gaps and use factory mounting points. Verify alignment with your door jamb before final fastening, and refer to your service manual for fastener torque specs.

What prep work is needed before painting?

Sand the primer surface lightly with appropriate grit to promote paint adhesion, then clean off all dust. Apply your chosen primer and topcoat according to the paint manufacturer's instructions. The FRP is ready to accept paint right out of the box.

Will these crack or flex if I bump them?

FRP is rigid and resists impact better than thin plastic, but door caps can take contact. Avoid slamming doors and inspect mounting fasteners periodically to ensure they remain tight. Proper installation is key to longevity.