By positioning this "Bomb" at a key point in the system, increased performance and flow is achieved through the expansion and contraction of exhaust sonics through the system. Result is a flow increase of nearly 10%! The outer chamber in the Powerbomb allows the air to expand, cool and ramp back up at a higher velocity. Additionally, the PowerBomb is a "pre-muffler" of sorts which helps to lower the bikes sound output by providing more sound absorbing surface area for the sound medium (exhaust gases). On some models, you can choose between a moto or supercross version.The supercross version is designed for more low to mid-range power where the moto version is focused in the mid to upper RPM range. Notice:Closed Course Use Only. This item is in the category "eBay Motors\Parts & Accessories\Motorcycle & Scooter Parts & Accessories\Exhaust & Emission Systems\Manifolds & Headers". The seller is "mypowersports_com" and is located in this country: US. This item can be shipped to United States.