We have front license plates in Texas, and the bumper-mounted plate was making it difficult to replace the grill. (The license plate frame is right in front of the lower/bumper grille, blocking it.) I couldn't remove the license plate frame because the last time I did that the nuts behind the bumper fascia fell down and I couldn't put the plate back on without removing the bumper. After many attempts, I realized I could just pull the bottom of the license plate frame forward, flexing the bumper slightly, but causing no damage. I was then able to slip the lower grille in from below. I never took off the bumper as others here have said is necessary. Note that my P5 has always been garaged day and night, so all the soft parts on it are still flexible.
As for how I removed the old, broken grille, I couldn't figure out how to do that nicely. I ended up compressing the locking tabs as much as I could, then finally resorted to ripping the damn thing out. It broke the tabs in the (broken) grille, but not the corresponding slots in the bumper fascia. So no problem upon installing the new grille.
