would any problems arise from molding fiberglass on to a stock bumper. would the different expansion/contraction properties play a role and cause the paint to spiderweb or anything like that? does anyone have experience with doing this? i know people mold sideskirts to the body of the car all the time. i figured i would ask here before approaching a body shop. btw...i wasnt going to try it myself, i would have a professional do it. thanks for any help.

Fiberglass will not bond properly to a stock urethane bumper that flexes a lot. I would never do that. I doubt it would last long...

it wont last at all, only certain materials can bond to other materials, fiberglass is a thermoset plastic which means it is molded and stays that way, our stock bumpers aren't they are thermo (something, went blank on the word) which are plastics that have a memory and will go back to shape usually with heat. You can't bond the two together.