Todd's video shows them, that is how I learned where to install mine. From my experience over 150 miles, you will want both. I jet for one open and one closed and I use them both a lot. With them in the back of the airbox lid, you can open or close them as needed for your driving conditions without taking off the top plastic that covers the airbox.
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Teryx How-To and mountain riding Videos
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2008 Teryx LE - Muzzy's Exhaust - Dalton Clutch and OD Cover - FST Std Bore Kit - Dynatek Programmable CDI and Coils - Hunterworks Carb Kit - Walker Evans Shocks - PRP Seats and Crow Harnesses - UNI Filter with HW TPI Valves in Airbox - Bighorns - Unisteer PS - Baja 540C GPS - Coming soon, SDR 4 Seat Cage and Front Bumper