05-17 HONDA CRF450X: FMF Q4 Hex Spark Arrestor Slip-On Exhaust The FMF Q has always been in a league of its own and the latest Q4 is the most significant upgrade to date. You don&#39;t need to settle for a plugged-up moto muffler hampered by an insert when you can have a compliant muffler engineered for performance.Less sound equals more ground.Meets U.S.F.S. and FIM World Enduro sound regulations.Power gains throughout the entire RPM range.Spark arrestor included.Pounds lighter than stock.Rugged design for off-road endurance.Only U.S. manufacturer to offer dedicated quiet exhaust systems.Can be used with FMF or stock O.E.M. header.Made in the U.S.A.Note: For closed course competition use ONLY.