I'd get a panel filter personally, it may have "over double the surface area of a standard panel replacement" but there is a a reduction in the size of the hole it has to go through compared to the surface dimensions of the panel
A cone is OK if mounted directly on the intake as the inlet is the same size but I can't see any gain in putting it in the standard air box
A cone is OK if mounted directly on the intake as the inlet is the same size but I can't see any gain in putting it in the standard air box