Hand TIG-welded stainless steel construction 1-3/4ö headpipes step up to 1-7/8ö into the collector to increase flow and improve performance 4" diameter straight can 11" muffler body includes matching aluminum end cap Removable spiral-core perforated baffle features an all-new aggressive sound Features 18mm and 12mm O2 ports with adapters and plugs Full coverage stainless steel heat shields for the front and rear header pipes included Made in the U.S.A. Fits Dynas with mid-controls '91-'17 and forward controls '07-'17. EXH 2:1 SUPER FX 91-17 SS