I replaced the stock 550 grilles in my car shortly after I purchased it as all the top retaining clips that hold the grilles in were broken, that's why they kept sticking out at the inside corners. I wanted M5 grilles, but they weren't available yet so I purchased the 528/535 grilles since they look a little sportier than the chrome/silver 550 grilles.
There was a thread on here awhile back on how to make M5 grilles by scraping the chrome off the fins. I purchased a pair of grilles off a member here on the boards and gave it a shot. Instead of scraping, I just sanded the chrome off with some fine emery cloth I had laying in the garage. Then I gave them a couple of quick shots of satin black Krylon for plastic, let them dry and snapped the grilles back into the chrome trim rings.
I installed them today and found that when I took my car back to the dealer to have them repaint the front fascia as it was blistering by the headlight corners, they didn't even pull the grilles, there was a paint mark on the edges of the trim rings and there was all sorts of prep slop in openings.
....enough bitching, here are the final results:
Before (don't mind the mess in the garage)
After
Here's a pic of mess in the grill opening
This is just a taste, I hope in the next couple of weeks my Morrs will be in so I can get my car lowered. When that happens I'll post more pics.