i was talking to a guy at my local hobby shop and he asked me if i had ever tried to breath though a tmaxx 2.5 air filter. so i tried and it was like trying to breahe though steel.....it aint goin to happen. so i decided to get a proline air filter and i could tell a diff in my proformance. cause the 2.5 air filters are basically starving the engine of much needed air. well that my storie. any imput would be cool.