HMF Exhaust Performance Series Slip-On Brushed Polaris Outlaw 90 2007-2014 Setting the standard for power and value, the HMF Performance Series has been track tested with over a decade of championships. The specially designed, unrestricted core provides maximum flow and allows the exhaust to increase horse power and torque evenly throughout the entire power curve. The trademark to the HMF Performance Series is the exhausts sound. With a deep, aggressive sound, youll typically see a 2-10 dB increase from the stock exhaust system. And with industry-leading end cap and color options, you are sure to add a completely custom look and sound to your machine.