Slip-on system comes with stainless steel slip tube and brushed aluminum canister. The M-7 slip-on exhaust system adds over 10% more HP, and pulls stronger all the way through the powerband. The stainless/aluminum system even comes with a removable, factory installed U.S. Forestry Service approved spark arrestor screen. Aluminum is a very lightweight and strong material used extensively in the aerospace, automotive, and of course, motorcycle industry. Aluminum is a wise choice due to its excellent strength to weight ratio, corrosion resistance and clean look. Lightweight, thin-wall .060 extruded 6061 aluminum alloy that is heat treated to a T-6 condition for increased strength, durability, hardness and finish hold is used. After the aluminum has been heat treated, it is cut to length and given either a polished or brushed satin finish. Ounce for ounce, aluminum is the best value of the M Series mufflers. As a rule the aluminum mufflers weigh about 8.3oz. more than Titanium or Carbon Fiber mufflers.