All Aero Performance Exhaust Stealth mufflers are 100% stainless steel and lap-joint welded for solid construction and reliability. Mufflers are packed tight with 3000 Degree acoustical ceramic material which is the best possible packing material on the market. The Stealth line is a free-flowing, straight-through perforated stainless steel core muffler featuring stainless mesh wrap and acoustical ceramic fiber fill to deliver that smooth, deep tone. Backed by the best Lifetime Warranty of any muffler manufacturer.