Will this interfere with the trunk lid when fully open?

The AF-6 profile sits above the trunk edge and does not obstruct lid travel. Verify clearance with your trunk's full swing range before final fastening; some aftermarket lids or modified hinges may require additional fitment work.

What's the best way to prep the FRP surface before painting?

Sand the bare finish with medium grit to establish adhesion, then move to finer grit for a smooth base. Wipe down with a tack cloth to remove dust. Use a quality epoxy or polyester primer rated for composite substrates before applying topcoat.

Does this wing require any reinforcement or bracing underneath?

The FRP layup provides inherent rigidity for highway speeds. If you're adding significant downforce mods or running extreme angles, consult your vehicle's service manual or a suspension specialist to confirm trunk lid mounting integrity at your target load.