hello im interested in purchasing a bmc cda airfilter at the moment as i could possible get a second hand one a bit cheaper. the problem id that i am confused by their sizing of their air filters please bear with me as i need some else's ideas on this i copied this off their web site which gives their sizing for the cda filters The CDA filtering system is a cylindrical shaped Carbon Airbox containing a washable, regeneratable filter. Replacing the original filter box with the CDA one, the fresh air flows directly to the filter and is taken in by the engine through a flow switch with minimu