fiberglass costs less, breaks easy, and is more expensive to install because of fitment problems. urethane is more expensive, wont crack and break unless u get hit or something, and u give it to ur body man and ur golden as far as instalation goes. with the extra money ur gonna pay for paint/body with a fiberglass kit u could spend a little bit more and get a urethane kit painted/installed. have u looked into any front lips tho....those are nice and sleek.