The headpipe merges into a large 2-1/4″ collector that steps up to a 2-1/2″ core. Core is perforated and wrapped in a stainless steel screen, then enclosed in a fiberglass pillow. 4″ muffler body capped with a 4″ machined aluminum dual-cut tip. Body can be rotated upward from its stock position. Works wtih stock or extended bags. Made in the U.S.A..