HMF EXHAUST Competition Series: The Competition Series was designed and tested for Sport ATVs. It features 3 inserts that effect the sound and power differently, giving you complete control over the type of power and sound you need, when you need it. The Competition Series features three removable inserts that change the power and sound levels of the exhaust. With a simple insert change, you can dictate the type of power and sound you need, when you need it. Arguably the highest performing after-market exhaust on the market, the Competition Series is a pure blend between optimized performance and versatility for sport ATVs. The secret to the Competition's unique power increase. The Trimax Core has a triangular shaped portion that unleashes large horse power and torque gains in specific race fields of the RPM range. Free spark arrestor with each muffler ordered!