WHAT IS IT? The FMF Racing Powercore 4 HEX Kawasaki KX450 muffler is the cheapest slip-on power option offered by FMF Racing. With race-inspired performance at an economical price, the Powercore 4 HEX muffler was created to improve power and durability at a price that won’t break the bank. 

WHAT’S IT COST? $359.99.

CONTACT? or (310) 631-4363.

WHAT STANDS OUT? Here’s a list of things that stand out with the FMF Racing Powercore 4 HEX slip-on muffler.

(1) HEX. The “HEX” terminology comes from the hexagon-like shape of the muffler’s end cap instead of the standard oval. The hexagon shape was used to work with the updated Hi-Flo internal core structure and increase airflow, power and torque. Along with the uniquely shaped end cap, the Powercore 4 muffler was built with stainless steel and aluminum materials. It weighs more than titanium mufflers, but it’s more durable. 

(2) Stock power. Since the Kawasaki KX450 got big updates in 2019, the bike has remained almost the same. The 2020 model was unchanged, and the only internal update on the 2021 model is in the clutch. The modern KX450 engine isn’t known for its horsepower or torque, as it ranks near the bottom of almost every rpm on the curve. What it is known for is delivering a brisk and snappy response at the throttle that allows riders to put power to the ground easily. Power is great, but only if the bike and rider can use it. Kawasaki’s selling point for its latest 450 is nimble handling, not horsepower. 

(3) Performance. The Powercore 4 HEX slip-on muffler gave our 2020 Kawasaki KX450 an extra boost in the low end and carried that boost all the way through the rpm range. Our faster testers appreciated the FMF muffler and never wanted to take it off. It was more exciting to ride and easier to stay in each gear longer without having to shift as often; however, our slower testers felt that it was harder to get into the power when they made mistakes. They found the stock muffler picked up slightly quicker at the crack of the throttle, and they liked it better in tight corners.  

(4) Details. The FMF Powercore 4 HEX KX450 slip-on muffler is 2 inches shorter than the stock muffler, which drastically improves the bike’s aesthetics and cuts weight by 1 pound. It also makes the KX450 sound like a motocross bike instead of a trail bike.   

(5) Options. In the slip-on muffler department, FMF Racing offers a range of products to meet racers’ needs at multiple price points. The lightest, fastest and flashiest muffler with all the bells and whistles is the titanium Factory 4.1 RCT slip-on with the carbon end cap. It retails for $574.99. Next is the same titanium 4.1 muffler but without the carbon cap. It costs $524.99. The stainless steel and carbon-capped version is $449.99. The Powercore 4 HEX muffler we tested isn’t as light or advanced as its siblings, but we didn’t mind, because it serves a different purpose. For $90 less, the Powercore 4 HEX muffler is more affordable and more durable at just $359.99. 

WHAT’S THE SQUAWK? Our slower testers wish that it could have kept the same throttle response the stock muffler provides.

MXA RATING: The FMF Racing Powercore 4 HEX slip-on made our KX450 more exciting to ride. It allowed us to keep up with other 450s down long straightaways while also fixing the nightmare of the long and ugly stock muffler and its weak tone.  

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