Will this diffuser hang low over steep driveways or parking lot inclines?

The diffuser extends below the factory rear bumper line. Before installation, measure your driveway approach angle and parking spots to confirm adequate clearance. Many owners adjust their entry speed at steep angles — common practice for any aftermarket rear body work on lowered vehicles.

Is this purely cosmetic or does it actually improve airflow?

AMGT-style diffusers are designed with functional geometry to manage rear underbody airflow and reduce lift at speed. Whether you'll feel a measurable performance gain depends on your driving conditions — street use vs. track use yields different results. The styling and aerodynamic intent are both real.

What prep work does the FRP panel need before paint?

Sand the surface and fill any imperfections with body filler as needed. Once prepped, apply your chosen primer and paint system per the manufacturer's instructions. FRP takes paint well when surface prep is done right.