Well, I thought I give this a shot.
Part # is 997-575-327-90-01C "Hider", it's also called the upper grill. Cost of the mod was 30 for the grill and 2 for some black silicone.
Total time to do this about 1.5 hours, taking my time.
Tools: Dremel and some sandpaper.
Procedure was straight forward, place grill on top of bumper cover, outline cutline, use Dremel to cut, smooth edges, glue in using the silicone. I also painted the bumper black (that's the aluminum bar) so it does not shine through.
Notes: The grill is just a bit too wide so it can't go right below the hood line but a little lower. I did not trim the left and right "overhang" of the grill. I think I leave it as it is for now, maybe later. The grill itself follows the bumper cover profile perfectly!
I did not change anything else, I still search for the right part#s to do the front radiator relocation and shrouding. Anybody have this info?
Looking forward to your comments fellow Boxsters!!
Later,
Andy