I've had this problem for a while, and the bumper isn't even on my car anymore for now because of this.
look at this picture:
see how the bumper looks like it is bent? well, that is the metal bumper support that is pushing down on the urethane. It seems there is not enough allowance between the bumper and the metal support. btw, fitment is very easy, it's just not totally flush.
I don't know if my bumper is genuine, but then again, the paint is a genuine WK0 pearl white, it is definately black polyurethane, and I've never heard of a replica oem jdm bumper before. I bought it from a member here last spring. Does anyone know why my bumper is doing this? I can't just leave it alone because my turn signals cannot mount flat against the bumper.
I'd appreciate any ideas on why this is happening. I've thought of things like previous front end collision and repairs, bad bumper, interior foam support (I've tested fitment w/o it, and it still doesn't fit right). The car is a 98 and has never been in an accident.