I have a stillen rear valance that I want to "shave" one of the exhaust cutouts on to help with the appearance of my single exhaust. Any tips on the best material to use to fill that area and to make the bends of the valance would be greatly appreciated. I looked at either using part of my bothers spare OEM 240sx bumper or buying some ABS plastic and using my heat gun to mold it. I don't know how well either will hold up compared to the Stillen unit since it is such a "softer" urethane than the other riged materials.