aFe 49-36409 MACH Force-Xp 2 IN to 2-1/2 IN 304 Stainless Steel Cat-Back Exhaust SystemaFe 49 36409 MACH Force Xp 2 IN to 2 1 2 IN 304 Stainless Steel Cat Back Exhaust System aFe is proud to introduce the aFe cat back exhaust system for the 2005 2008 Porsche Boxster S and 2006 2008 Cayman S (987. 1). In recent testing with the aFe dual tip assembly, this exhaust system resulted in a max gain of 29 horsepower and 40 lbs. x ft. of torque. aFe spent countless hours of R&D to develop the perfect balance of pure, race inspired performance