Take your pick between Helix or ER. Both are great units that performs great so it'll be which you you prefer. If you want a nice piece to show off, Helix. If you want a stealth unit and have the sleeper effect, ER anodize black.
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