MXA TEAM TESTED: 2024 YZ450F TWIN AIR POWERFLOW KIT/SRP HIGH FLOW AIRBOX COVER

WHAT IS IT? The Twin Air PowerFlow kit comes with a rigid, lightweight, aluminum cage and dual-layer, flame-resistant, domed air filter. It is designed to eliminate the dirt migration issues of the stock YZ450F air filter while increasing airflow.

WHAT’S IT COST? $249.95 (PowerFlow kit), $36.95 (Twin Air filter), $100 (SRP High Flow cover).

CONTACT? www.twinair.com, www.srpinternational.com or www.rockymountainatvmc.com.  

WHAT STANDS OUT? Here’s a list of things that stand out with Twin Air’s YZ450F air system.

(1) Stock 2024 YZ450F air filter. The stock 2023–2024 YZ450F airbox comes with a domed air filter, higher-volume airbox cover and a new filter attachment design. All of this is good, but the goodness is ruined by the fact that dirt can migrate under the filter cage, especially at the very front of the filter (be sure to check it closely after every ride and grease it heavily).

The air filter leak issue is caused by the rubber strap that is supposed to hold the front of the air filter down. It needs to be tighter to secure the seal at the front of the filter.

(2) Twin Air PowerFlow air filter. Twin Air recognized the sealing issues with the stock YZ450F air filter and designed a new air filter that addresses the leakage by equipping the new filter with two round grommets, front and rear, that slip over the alumuminum posts to hold the filter securely in place.

Additionally, the Twin Air Power Flow kit comes with a high-quality, dual-layer, flame-resistant air filter, anodized aluminum cage (minus the backfire screen), and a small aluminum L-bracket (shown below) to hold the filter/cage securely in place. Twin Air’s system eliminates any dirt going under the filter. 

Twin Air’s aluminum cage removes the backfire screen to help throttle response, but this increases the risk of dirt falling into the intake tract when removing the air filter. MXA keeps a small shop vac handy to suck up any dirt that falls into the throttle body.

(3) SRP High Flow airbox cover. MXA decided to combine the Twin Air PowerFlow kit with a Slater Skins High Flow airbox cover. Initially, we were hesitant, because the 2024 YZ450F is already so hyperactive that we weren’t positive we wanted more wheelie-inducing power. Surprise! The $100 Slater Skin (SRP) airbox cover and $250 Twin Air PowerFlow kit made the YZ450F rev quicker, which made the power more useable. We expected it to be a beast, given that the combo adds over 2 horsepower to the already hooked-up YZ450F. We thought it would wheelie over backwards with the added power, but instead, the quicker rev just broadened the powerband.

WHAT’S THE SQUAWK? Three quibbles: (1) The vented Slater Skins airbox cover increases the noise emanating from the airbox to “Twisted Sister” decibels. (2) Although we are big advocates of removing backfire screens, it probably isn’t such a good idea on a downdraft design. (3) At $350 for the PowerFlow kit and SRP cover combo, it is an expensive upgrade.

MXA RATING: Most MXA test riders prefer to tame the YZ450F power delivery with the mellowest map we can install, leaving only our pro riders in the market for more horsepower. For those pros, the Twin Air/SRP combination is a win-win, but most YZ450F riders would be happy with the gains made by just installing the latest grommet-equipped YZ450F Twin Air filter.