MXA TEAM TESTED: TWIN AIR 2024 KX450 POWERFLOW KIT

WHAT IS IT? With each OEM’s airbox being different, the PowerFlow kit is designed specifically for each brand’s and model’s needs for improving airflow and durability. Most PowerFlow kits don’t come with as many parts as this one, but the 2024 Kawasaki KX450 airbox needs more help than most. The PowerFlow kit completely redesigns the airbox.  

WHAT’S IT COST? $214.95.

CONTACT? www.twinair.com or your local dealer. 

WHAT STANDS OUT? Here’s a list of things that stand out with the Twin Air PowerFlow kit for the 2024 Kawasaki KX450.

(1) 2024 KX450. Kawasaki went all out with a new engine and chassis for the 2024 KX450, but they suffocated the engine. The stock setup uses a flat-piece-of-toast-style air filter with less surface area than a standard filter; it doesn’t seal properly, and it hinders airflow. 

(2) Regulations. Why would a manufacturer go all out on 99 percent of the bike just to sabotage the engine with a horrendous airbox and air-filter design? The answer is noise regulations. Kawasaki is looking ahead to 2025 when the FIM introduces the new, stricter, 109-decibel sound regulations for the MXGP series and the 2026 AMA Supercross series. This airbox, along with the stock muffler setup, mutes the four-stroke noise. Unfortunately, the reduced noise also comes with reduced power. 

 (3) Concept. Twin Air works closely with many factory teams, including the factory Kawasaki teams in Europe and the U.S., who helped them develop this kit. The Twin Air PowerFlow kit comes with a glass-fiber composite cage, a base plate, and a pre-oiled domed air filter. The Twin Air base plate replaces the slide-in stock KX450 airbox design and allows you to use the new Twin Air PowerFlow cage and filter, which snaps into place at the rear and uses a KTM-style grommet for securing the front of the filter. 

(4) Installation. Installation isn’t simple by any means. Twin Air has a video detailing the process. We recommend doing it in the garage and not at the track. In short, the subframe must be removed, and the stock air filter base plate must be removed with multiple screws and bolts before the Twin Air setup can be mounted. It took us 20 minutes to make the switch while following the YouTube tutorial video. 

(5) Performance. On the track, the power improvement was negligible. Our test riders didn’t notice a huge difference with the PowerFlow kit alone. On the dyno, the Twin Air PowerFlow showed slight improvement in the midrange and again in the top-end. It brought our stock KX450 up from 57.3 horsepower to 57.9 horsepower and improved torque from 35.6 to 35.8. It did stop dirt and dust from sneaking past the air filter and being sucked into the engine, which has been a huge concern since day one on this new bike. 

Although the PowerFlow kit didn’t wake up the KX450 dramatically by itself, once paired with an FMF or Pro Circuit slip-on muffler, it helped bring the KX450 to life. The stock setup hinders airflow going in and out of the engine. With FMF and Pro Circuit helping the KX450 exhale, this bike became a lot more enjoyable to ride. We also recommend removing the stock rubber plug at the top of the airbox. Twin Air makes a vented plug for $62.95 that allows air in and keeps dirt out. 

(6) Pro Circuit race mod. Pro Circuit trims the green plastic surrounding the air filter and adds its T-6 slip-on muffler. With this setup, the KX450 dyno curve was drastically changed. The peak horsepower gain was minor, the midrange boost picked up sooner, and the peak torque went from 35.6 to 37.7 pound-feet with a beautiful power curve filling in the massive dip in power of the stock KX450.

WHAT’S THE SQUAWK? Installation is not a quick process. Take your time and keep track of all the bolts and screws you remove.  

MXA RATING: The Twin Air PowerFlow kit shouldn’t be thought of as a power-producing hop-up mod; instead, it promotes longevity by allowing your air filter to seal properly, protecting your engine from dirt and dust going down the intake.