Royal Muffler of Chatsworth, USA made a custom quad setup for the new F10. Here are some photos of their work, and the sound tests as well. Enjoy!
Source: 5post

Royal Muffler of Chatsworth, USA made a custom quad setup for the new F10. Here are some photos of their work, and the sound tests as well. Enjoy!
Source: 5post
Hot on the heels of its world premiere here in Munich, the new BMW i3 …