From GT Purely Porsche Magazine:
SharkWerks gets its teeth into the 997 GT3 and RS
American Porsche specialist, SharkWerks has developed a stainless steel exhaust system for the 997 GT3 and GT3 RS. It not only increase the engine's power and torque figures (when coupled to the company's engine management upgrade), but also reduces the weight at the rear of the car by 28 kilos.
Manufactured from stainless steel, the system allows for the factory headers and catalysts to be retained, which means you won't get any check engine warnings lights flashing at you from the instrument panel. It also utilises the factory fixings and fits all 2007/8 GT3 and GT3 RS models, as well as the latest 2010 GT3. Visit www.sharkwerks.com for more information
and videos of the exhaust: