Do these diffusers require paint preparation before installation?

Yes. Sand the mounting surface of your OEM bumper lightly to clean off any dirt or wax, then install the spats dry-fit first to verify alignment. Once positioned, you can mask and paint both the diffusers and the bumper as a single assembly for seamless color match.

What hardware is required to mount these to my bumper?

The diffusers mount at existing OEM bumper reinforcement points. Verify your bumper's tapped holes or mount pad locations before purchasing fasteners — you'll need corrosion-resistant hardware rated for exterior plastic-to-plastic or plastic-to-metal interfaces. Check your vehicle's service manual or OEM bumper documentation for correct fastener specifications.

Will these fit with an aftermarket exhaust or diffuser system already installed?

These are bumper-mounted spats, not exhaust diffusers. Clearance depends on your exhaust tip diameter and exit angle. Test-fit the spats before fastening to confirm the lower edge sits clear of any exhaust pipes or tips. If you run a catback system with a low-exit design, measure the tip-to-bumper distance carefully.