All out power and performance Setting the standard for power and value, the HMF Performance Series has been tested for over a decade with endless championships. The specially designed, unrestricted core allows the exhaust to increase power evenly throughout the entire power curve. The Performance Series has the signature HMF sound with industry-leading end cap and color options, giving you a completely custom look and sound. Developed for ATVs, Dirtbikes, and UTVs. Distributes power evenly throughout the power curve. Sound levels 4-6 dB over stock. (varies per model) 2-1/8‚ non-restrictive core. Proven with over a decade of endless championships. EXHAUST SHAPE: Depending on the model of the machine, the Performance Series is available in Round and Elliptical Shells. SYSTEMS: Depending on the machine, the Performance Series is available as a Slip-On or Full System and developed for ATVs, Dirtbikes, and UTVs.