Its been known for a long time that the std airbox (06+ especially) are the best intake for performance if you are running an NA stock-ish Zed. Remember, Nissan know their stuff, they know how much air the engine needs, and until you take it well out of its comfort zone (ie stroker kit or FI), the std box with performance filter will be the best bang for buck going. However the noise of the open filters is awesome, and once moving, I'm not convinced that the sealed airbox will give much better performance than enclosed as we saw in Andy's thread