The real M5 grilles have 12 fins. I ordered mine through BMW and got one with 10 and one with 12. I'm waiting for a 12 to complete my car.
This one is at the dealer with a 10K markup
2011 550i Xdrive, Sophisto Grau, Anthracite/Black Dakota, Active/ventilated seats, Cold Weather, Convenience, M Sport, P2, SAT, HUD, top and side view cameras, power rear sunshade, split fold down seat, comfort access, SAT Radio, rear view camera, 35% window 3M tint, Dinan Stage 1 (soon)