What is a good aftermarket air filter for the MT2 and ATX? While cleaning out the air filter I have noticed fine dust particles inside the rubber tube the air filter is fitted into. I am currently using what came stock with it, but am wondering if there is a better filter out there. Or, is this just common. We were running around on the baseball field and did stir up a bit of dust. Does anyone have a filter you have found better than others?