Features full 2" left side crossover and 4-1/2" muffler bodies with 2" inlets. All M8 systems feature: 1-3/4" to 1-7/8" to 2" high-flow 16-gauge three stepped primary headers. Enlarged interconnected headers make for improved horsepower and low-end torque. 2-1/2", 220° 16-gauge heat shields. Baffles are wrapped in stainless steel wool and high-temp fiberglass for a rich mellow tone. Heavy-duty AccuSeal® reaction-block header-to-muffler clamps included. 18 mm and 12 mm O2 bungs welded into the primaries. Optional inserts boost low-end performance (available separately). Made in the U.S.A..