The RoadsterSport 4 Cat-Backstainless steel exhaust system offersgreat performance with a mild sound thanks to its newly included"Helmholtz chamber". Built from T-304 polished stainless steel, including the hangers, this exhaust features features a standard resonator in the connecting pipe to lower volume and rasp, and an exclusive all Helmholz main chamber at the back that massively reduces the standing wave 'boominess' inside the exhaust system! Cuts the 'booming' frequencies of 120-130hz by over 40+db inside a top up Mx5 cabin. This system also includes removable baffles that you canuse to control the sound level. Includes mounting hardware and gasket, as well as a lifetime warranty from the manufacturer.