When designing the PowerCore 4 HEX, we looked at our top of the line products to deliver race-inspired performance at an economical price. The end result is a quality muffler with improved torque, increased horsepower and rugged durability all at a price that won't break the bank. -Overall increase in power and torque. -Durable stainless steel and aluminum construction. -Space Age internal packing material for maximum longevity. -Internal shape of core uses Hi-Flo technology. -Enhanced sonic evacuation provides for higher flow and increased power. -Includes removable spark arrestor. APPLICATIONS Make Model Year GAS GAS EX 250F 21-23 GAS GAS EX 350F 21-23 GAS GAS EX 450F 21-23 GAS GAS MC 250F 21-23 GAS GAS MC 350F 21-23 GAS GAS MC 450F 21-23 HUSQVARNA FC 250 19-22 HUSQVARNA FC 350 19-22 HUSQVARNA FC 450 19-22 HUSQVARNA FC 450 ROCKSTAR EDITION 18,20-21 HUSQVARNA FX 350 19-22 HUSQVARNA FX 450 19-22 KTM 250 SX-F 19-22 KTM 250 XC-F 19-22 KTM 350 SX-F 19-22 KTM 350 XC-F 19-22 KTM 350 XC-F KAILUB RUSSELL 21 KTM 450 SX-F 19-22 KTM 450 SX-F FACTORY EDITION 18,20-21 KTM 450 XC-F 19-22 Fits: Gas-Gas EX250F 2023 EX450F 2023 MC250F 2023 MC450F 2023 GasGas MC250F 2021 MC450F 2021