single. i feel like the double is too much, it only looks good on an actual M car imo.I would say glossy black on carbon black might look better but either way you go it will look nice, I personally have single slat matte black. Have you considered if you're looking to get the single slat or the double slat grille?
Here's a thread that might help http://f10.5post.com/forums/showthread.php?t=1225728
that sounds really nice. do you have some pics i could see??I went with glossy. I powder coated my wheels with a semi-gloss black so it matches. I also went off the color of the pillars on the doors. The black was a gloss on those from the factory. Everything matches that way.