Thanks. I am also concerned about the quality of the kit. It will be a replica and I know there are some inherent fitment issues with them, so which one would be easier to install/modify and make a good fit.
Urethane is lighther than well enforced stronger fiberglass. The only down side is the manufacture. Fiber glass is much easer to mold. urethane must be heated to a liquid and poured in to a mold. Urethan looks much better because it is smooth where fg has natural waves in the material. Urethane also takes abuse much better. This is why all car manufaturers use urethane and no fg.