I hope you can see the following link without having to register for the website that I am getting it from...

http://www.club202.com/forums/showthread.php?threadid=1711

Its by a hard-core Mercedes enthusiast who works at a shop and they do exhausts for big name companies (He couldn't say who, but I guess some tuner brand contracts them to make their exhausts). His exhausts are getting good reviews by the W202 AMG owners, and I bet their price is good. They also have done some other high end cars like new Porsches and Maseratis... not bad for a newer company.

He claims dyno shows 17-22hp gaind after multiple dyno runs on their C43 exhaust, which looks like this in comparison to OEM AMG exhaust...