That is the Starting Line Products air box mod. Lots of people on this forum are running it as opposed to a Power Breather or TPI vavles. It draws cooler outside air instead of warmer underhood air. Combine it with SLPs' pre-filters for the footwell intakes and you'll never have to worry about the carbs icing up if powder riding is an issue. I installed V Force 3's at the same time as the air box so I don't know the exact gains for the box alone but it definately helps. Only drawback is it's size-the lid pretty much covers the carbs.
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