Anybody have direct experience with the OTR air filter set up?

http://www.off-the-road.de/XT-660/XT...ilter-set.html

It appears to be a direct replacement (ie to fit in the same manner) as the OEM paper filter. Is this so?

Why is it necessary to replace the airbox cover to fit it?

Alternatively, open to suggestions of other brands of oiled foam element, if anyone knows of any?