FMF Racing Q4 Hex Aluminum Slip-On Muffler w/Stainless End Cap for Yamaha YZ250F 14-18/YZ250FX/WR250F 15-19FMF Q4 HEX Spark Arrestor Slip On Exhaust Yamaha YZ250F YZ250FX WR250F Loud pipes might save lives on the street but in the dirt sound is the number one killer of riding trails and regulated track hours. If you have been searching for a performance enhancing muffler that does not wake the dead, then the FMF Q4 HEX is the muffler for you. FMF approached the design process of the Q4 HEX with the goal of achieving more power while keeping noise levels to