As the forum's self proclaimed body kit expert, short of a company in California called MA Shaw, who was at one time able to source the oem GT3 bumper a few years back, I can't recall anyone else who had it. There are , however, a few high quality, TUV certified FRP versions that are available. Certain that it is, there are benefits to a bumpers and aero parts that are manufactured from polyurethane. However, take it from someone who has explored this topic ad infinitum et ultra, if an aftermarket part that is made from poly doesn't fit precisely (and I've seen plenty), you're SOL by virtue of the fact that said material cannot be manipulated. Whereas FRP can be "crafted" in any way imaginable in order to achieve a perfect fit. The downside to FRP, and carbon fiber for that matter, is that it does not withstand impact well.
p.s. That 997 GT3 bumper from NR Auto, along with all of the others,, is an abomination ! The way the areas for the driving lights have been backfilled is nothing short of a contrivance !