Exhaust Muffler Assembly. Walker® is the only aftermarket exhaust manufacturer in North America with the capability to combine industry-leading coverage with a direct fit OE-style replacement, 100% structural stainless steel muffler, which provides more than three times the average lifespan of competitors; aluminized replacement mufflers. Walker® Quiet-FlowSS is available for many popular European, Asian and North American vehicles. In addition to Walker;s renowned precision fit, superior flow, and OE-style sound, these mufflers feature 100% stainless steel heads, shell, bushings, louvered tubes and partitions. Walker® Quiet-FlowSS mufflers have a Limited Lifetime Warranty and a 90-day Safe and Sound® guarantee.