I would go for the rear deck spoiler.
Later on, I would then buy a complete Sport bumper that will hopefully be more aggressive than what the CF lips offer.
I think the CF lips are cool, but since the Sport bumpers are beginning to show up, I would rather wait and get a more complete package/kit (front and rear bumpers).
E90 330i 6MT|Space Grey|Red Brown|Alumin|Sunroof|Voice Control|Logic 7|Xenon|Prof-Navigation|Storage Pack|Luggage Pack|Extended Lights|Anti-dazzle Folding Mirrors|Climate Comf. w/screen|M-Sport Pack|Exclusive Pack|Innovations Pack|Alumin Pedals|CF Splitters|Delivered:19 March 2010