Off the top of my head, BC Racing, KW V2, and Bilstein PSS9 (maybe PSS10 if you find a sale). I'm sure there are plenty more but these are some of the popular ones on the forum. If you keep searching this section, you'll find some pretty in depth reviews.
Cobb|ER FMIC & CP|MS DP & Stud Kit|aFe DCI|Spec Stage 2+| Recaro Profi XL| Bilstein PSS9|HRE 840r|CF GTR Vented Hood|OSS Design|Walbro 255|BMW Perf. Spoiler|Muteki Anodized Blue Lugs|HID Fog Conv.|Cusco Strut Bar|StopTech Power Slot Rotors, Street Pads & SS Brake Lines|Michelin PSS|Muffler Delete|RB PVC Valve|BMW SSK