Am using K&N performance filter in my Alto. Yesterday when i opened the Bonnet to do regular check up, i was little surprised when i observed the air filter. Its a conical shaped filter and at the bottom i noticed that some portion of it (say @2 cms or so) had become very soft (like melting). It had become powder type. The surface of the air filter is mesh type. To be specific, i observed a portion (@2cms or so at the bottom) of this mesh like surface melting.