[EPIQTodd]

Don't forget OEM parts as well - poly resin. Fiberglass is light and cheap - racers use it because of those reasons, and often racers have extra body parts with them at the track when they get hit, because fiberglass will shatter. It's not desirable for a bumper if you drive on the street. Whereas an OEM (poly) bumper may crack or dent, a fiberglass bumper will crack and shatter - far more damage and much larger crack than the poly bumper. Carbon fiber is the lightest, but also most expensive, and near impossible to repair properly.