Will this diffuser scrape on driveway inclines or speed bumps?

Rear diffusers sit low, so approach angle matters. Before committing to this profile, verify your typical approach angles and inspect your current bumper clearance at the lowest point. If you regularly bottom out on stock trim, you'll want to assess this one the same way.

Does this diffuser add real downforce, or is it mainly visual?

This is a Sika-styled diffuser — it's designed to complement your bumper's aesthetic. Real downforce requires specific ducting, diffuser vane angles, and vehicle speed optimization. Use this for the look; don't expect measurable aero gains on street driving.

What prep work does FRP need before painting?

Sand and prep the surface thoroughly before applying your chosen primer and topcoat. FRP accepts standard automotive paint systems — the key is surface prep, not the material itself. Follow your paint manufacturer's guidelines for adhesion and curing.