I'm running the Macht Schnell stage 1 (filter and scoops). Easy to install (MS provides great videos). Filter is high quality. Stack it up against the OEM and you will see the difference.
I think it is about $160 at EAS.
Unless you are looking for cosmetic changes the cost/benefit does not justify spending any more money.
2011 E93 - Space Gray - 6MT/Silver Novillo/
OE Tuning/Gruppe M Intake/ACS Springs/Vorsteiner CF Type I Rear Diffuser/Textured Matte Black Custom Powdercoated OEM 359s/Painted Reflectors/Matte Grille, Hood Vents and Side Markers/Arqray Race Exhaust/MS Pulley