I vote black. Flat black (or CF) as it gives it more weight and there are too many levels and layers to the diffuser design. If it's painted it will become too busy visually.
What spoiler is that?
Originally Posted by fresh_LA
This is the shot that inspired me to go OEM for the diffuser and spoiler...
looks like he has the diffuser painted gloss black throughout.
2013 Mineral Grey 335i | M-Sport, HUD, NAV, CF M Perf Trunk Spoiler, M Perf Grill