High Performance Exhaust Systems. There's really only one problem with the exhaust note of the first-generation XK8 & XKR: It basically doesn't have one. We offer several options to correct this deficiency. All of our exhaust systems are made in England from type 304 stainless steel. All pipes are bright polished. Mufflers are bright annealed. The final piece to the exhaust puzzle is a high-performance stainless steel front muffler. These are less restrictive straight-through designs and are about 20 percent lighter than original pieces.