The work that went into developing the RS-4 muffler design paid big dividends in 2010 with Ryan Dungey winning the AMA 450 Supercross and Motocross Championship series as a rookie in the same year, and again in 2012 with the Yoshimura-backed GEICO Honda team winning both 250 Supercross Lites titles. That same R&D has been directed to developing the current generation RS-4 — a unique design that provides an unrivaled combination of power and a quiet exhaust note. The RS-4 features a Polyresonant duplex chamber, a two-staged stepped baffle and an innovative carbon cone end cap.
Pentagonal-shaped sleeve
Stainless Steel sleeve for increased durability
Straight baffle for ample flow
Turn-down carbon fiber end-cap
Stainless steel tail-pipe.
Fitting Instructions: http://www.yoshimura-rd.com/images/192002D520.pdf
Race, Removable Baffle