The plastic is curved and made to fit under there so the flex of the part is not crucial/required for fitament but it is forgiving if the tape is a little bit buldging or if the holes were not drilled perfect etc. Just gives some play to make sure it looks right. I think to ensure a good fit the mould would almost have to be done while the part is installed on the bumper to make sure the curvature and fit is perfect. Basically use the bumper to create the flange if possible. Just a little bit of pressure or weight on the part by itself during molding could cause the curve to be off just enough to make it not fit perfect. I would love a CF set and could easily sell my plastic ones to pay for it afterwards but I have been burned a couple times at this point so I'm not as willing to jump in line anymore. If any of these parts start appearing and are quality though I would gladly jump on board for purchase.