mugen 1/8 air filter on stock traxxas neck = best airflow/filtering combo. You just gotta buy the mugen air filter, Then you know how the traxxas neck has the little ridge in it that secures it on the stock filter? Just cut the mugen filter open enough to were you can fit the stock neck in there. Then put some shoe goo or silicone around the whole thing and let it dry for a few hours. After that your good to go.