I bought a Timevalve system for my car and wasn't impressed, in fact I was so disappointed that after a few months of deliberating I bought a factory system instead, see my comparison here:
http://www.sl113.org/forums/index.php?topic=21397.msg171125#msg171125See reply #308 onward, I didn't think the welding was particularly nice, and I didn't like the look of the mufflers, the edges were really jagged and they aren't a proper oval, it all seemed a bit home made to me. Comparing the two side by side, the pipes entering and leaving the muffler looks to be at slightly different angles too, one of them must be right...
I'm very funny about exhausts, I see so many garbage custom made exhausts on the cars that go through my shop, and I find them very offensive. The Mercedes system looks like a much nicer piece of kit in my opinion, that being said obviously isn't going to last a s long so there's the trade off. I want to sell the Timevalve system but fear the shipping to the USA would make it uneconomical.