The Factory 4.1 is FMF Racing s premier performance exhaust. With over 35 years of racing experience behind it, the Factory 4.1 takes advantage of everything we ve learned on the race track. The Factory 4.1 is guaranteed to produce more horsepower throughout the entire RPM range. More power means better starts and less work getting around the track. Reduced weight means better handling resulting in less fatigue at the end of a moto. If performance is your priority, the Factory 4.1 is the only exhaust for you.

• Horsepower gains throughout RPM range
• Advanced engineering and patented design
• Meets AMA/FIM 94dB sound requirement
• Spark arrestor available for purchase
• Available in natural titanium or blue anodized fi nish
• Used by Factory KTM, Yamaha of Troy, JGR and Star Racing
• Use with FMF or stock header
• Easily serviced for repacking