Will this bumper work with my factory lower valance and undertray?

The AF-1 profile is designed for direct integration with OEM undercarriage components. Before installation, verify that your existing lower valance clears the new bumper geometry — minor trimming of plastic clips or brackets may be needed depending on your specific setup.

Do I need to sand and prep this before painting?

Yes. Sand and prep the surface before applying your chosen finish. FRP accepts primer and paint well once properly abraded. A quality clear coat is recommended to protect against UV and maintain gloss over time.

Is there a right way to mount this to avoid cracking?

Hand-laid FRP is durable under normal install stress, but even pressure distribution matters. Use fastener points aligned with the OEM bumper mounting scheme, and avoid over-tightening hardware — follow your vehicle's service manual for fastener torque values to prevent panel stress.