Will this interfere with my trunk seal?

Center-mount exhaust lips sit below the trunk line and do not contact the seal when closed. Verify that your exhaust outlet aligns with the center cutout before installation.

Does the exhaust cutout require drilling or modification?

The center port is pre-formed into the spoiler. If your exhaust tip diameter differs from the opening, you can carefully enlarge the hole with a Dremel or file. No drill-through required.

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

Sand the primer surface with medium-grit sandpaper and wipe clean before applying your chosen base and clear coats. FRP accepts standard automotive finishes and stays bonded through temperature cycling.