The Hooker Maximum Flow muffler actually flows 99 percent and produces more horsepower and torque than a 2-1/2 inch open pipe. The polished stainless Maximum Flow is constructed of all stainless steel for maximum corrosion protection, good looks and long life. They use a high temperature packing material to absorb excessive noise while allowing a mellow powerful sound. As with all absorption type silencers, the Maximum Flow will be most effective for sound control with lower compression (8.5 to 1 and lower) motors with conservative camshafts and with applications using catalytic converter(s). The Maximum Flow flows either direction, allowing for easy installation. Product Features:Flows 99 percentMore Horsepower And TorqueMore Horsepower And TorqueHigh Temp Packing MaterialAbsorbs Excessive NoiseMellow Powerful SoundFlows Either DirectionEasy Installation