Does this bar work with aftermarket bumper covers or only factory bumpers?

This reinforcement bar bolts to the frame at factory mounting points, so it's compatible with both OEM fascias and most aftermarket bumper covers designed for your generation Pilot. Confirm your bumper cover doesn't use a completely different mounting system before ordering.

Do I need to do anything special to the bar before installation?

The bar comes ready to bolt on. If your bumper cover is being repainted or if you're matching it to a custom color, remove the bar before that work and reinstall after paint cures.

Will this fit if I'm running a different front grille or lower valance?

The reinforcement bar mounts behind the bumper cover at fixed frame points, so grille and valance swaps won't affect fitment. Just make sure your bumper cover clears the bar during installation.