Akrapovic Slip-On Race Line (Titanium) for Porsche 911 Carrera and Targa (997)Akrapovic Slip On Race Line (Titanium) for Porsche 911 Carrera and Targa (997) The Slip On Race system provides even greater power and unburdens weight from the rear, offering better handling. The Slip On Race system, made of our proprietary titanium, includes side mufflers, a link pipe set with integrated exhaust valves, an X pipe, and four exquisite tailpipes. Add a Slip On Race system for even greater power and sound delivery, and the reduction in