Will this interfere with the factory lower bumper seal?

No. The lip extends below the fascia plane and mounts to existing attachment points, keeping it clear of weatherstripping and trim. Verify your bumper's cutout geometry matches the lip profile before fastening.

What's the best way to prep FRP for paint?

Sand the primer surface with fine-grit sandpaper and clean thoroughly before applying your chosen primer and topcoat. FRP accepts most automotive paints once properly prepped—follow your paint manufacturer's surface preparation steps.

Does mounting require drilling, or do existing holes work?

This lip uses factory mounting points on the fascia, so drilling is not necessary if your bumper has standard fastener locations. If your bumper lacks attachment holes in those positions, you'll need to drill carefully—reference your vehicle's service manual or mounting diagram for exact hole locations.