FMF 4.1 KTM 450 EXHAUST

PRODUCT: FMF Factory’s 4.1 RCT is a complete titanium exhaust system with a MegaBomb header, anodized-blue muffler and carbon fiber end caps for the 2016–2018 KTM/Husqvarna 450cc motocross and closed-course competition models. A Forestry Service-approved spark arrestor, Quiet Core insert and springs are included.

POSITIVES: We noticed a much more aggressive power off the bottom, and it pulled stronger through the midrange, retaining the same power surge on the top end. The two-piece header design makes for easy installation (stock is grim) and the complete system slips together without any issues. The FMF system is around 3 pounds lighter than the stock unit. With an anodized-blue can and carbon fiber end cap, the FMF system not only looks factory but it also delivers a deep, throaty sound.

NEGATIVES: Although we felt big increases down low and in the midrange, we felt no increased pull on top.

The metal springs connecting the header and mid-pipe didn’t have a rubber sleeve like in years past and would vibrate against the pipe at high rpm, creating an irritating vibration noise.

BOTTOM LINE: This system makes for increased power without changing the stock power delivery completely, substantial weight savings, factory look and the added bonus of a Forestry Service-approved spark arrestor. Hovering around the thousand-dollar mark, FMF’s Factory 4.1 titanium system is pricey, but they do offer a stainless steel and aluminum system that provides the same power increases for substantially less.

PRICE: $1049.99

CONTACT: Your local dealer or www.fmfracing.com