Air filter for s4rt s4rs

[DucDucGoose]

What is the best option for an aftermarket air filter DP, k&N,  BMC, do they all replace the lid? How does the cost compare vs actual performance gain?
I need some help

[Mojo S2R]

I have the DP Kit and it came with the open airbox.  IIRC it uses a K&N Racing Filter.  As far as I know this is the only one that comes with the open airbox.  There have been people on the board who simply buy the filter and then modify the box.  Just do a search for "open airbox" you should find all your answers.