The TurboXS RFL blow-off valve is our loudest and best-selling BOV. RFL stands for "Really ... Loud." This valve uses a special acoustic horn to focus the sound of the blown-off air, and it works. This is the loudest BOV we've ever heard, bar none. Click the !

Oh, and it's functional, too. Adjustable spring preload (using included washers) means it can hold as much boost as you want, and it can be set tight enough to not suck in air at idle.

Kit includes the valve, adjustable preload washers, flange, and all the required adapter hardware for your WRX.

Our most popular BOV!

Note: Installing ANY blow-off valve involves some compromise in driveability. When the BOV vents, the car will run momentarily rich. The adjustable valve can usually be adjusted to minimize any hesitation or stumbling, but hiccups or stutters are part of running an open BOV. If you're not ready for this, please do not install an open-to-atmosphere valve.

Includes valve, mounting flange, and vacuum hose.

Fits 2008-2014 WRX, and 2005-09 Legacy GT. Does NOT fit 2008-2014 STI.