just got these http://www.ebay.co.uk/itm/151097618283?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 http://www.ebay.co.uk/itm/160516795158?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 and how easy is it to take the air box off and do I have to take the charcoal filter off thank you