link 2 the 3ddesign e92 n55 quad exhaust thread:
http://www.e90post.com/forums/showthread.php?t=558531 (videos)
via: www.3ddesign.jp
Part no.: 4101-19014
Application: E90, 335i / N55B30A
Material: Stainless Steel (SUS304)
Control valve: yeee
Main pipe: 60.5mm
Tail pipe: 80mm / 4" tips
Contents: rear silencer
Installation: need to cut factory exhaust
Cost: $$$$$
