Pair of rear stainless steel silencers bought from BCS Powervalve in Aug '15 and used on my B8 S4. These provide a great change in noise quality, adding a little more throatiness and deep grumble while accelerating - they won't do your head in, and there's no drone from these either when fitted to a standard system.
Simply fit these in place of the standard rear boxes to hear more of that V6. I found the noise level when cruising to be as quiet as standard, with a nice level of added sound quality and volume when giving it the beans. Easy to keep clean, and being stainless steel, they should last a while

While both boxes are in fantastic condition, the bits you'll see (the tailpipes) are mint. Looking for £600.