I'm using a Pipercross foam type filter at present which repaces the bottom half of the standard air box.. still uses the standard air duct to channel the flow of air too. The filter works well and makes a nice but not stupid induction sound, it does require oiling for dust/dirt retention and I have heard a few people going on about the oil messing up the MAF. Is this a real problem? I have been using the filter for about a year now without any trouble but wondered if anybody has actually experienced any problems? Surely Pipercross have enough knowledge of cars not to produce a filter which damages the users car??