My S1 is very quiet comparatively. I'd had the car over 2 years when the factory informed me that it has big bore pipes whilst in for service! Don't know their origin or anything about the boxes except oval rear exits. I mainly use the car for distance stuff and certainly wouldn't swop it for a boy racer system.

1969 4/4
1995 plus 8
2002 Aero S1
2013 M3W
2014 Plus 8