Its a query regarding Nissan Altima. 6 months back I changed the mufflers of my car. Now it feels like the power has reduced very much. I don't know this is due to the replacement of mufflers. I remember when I consulted one auto repair and service centre in Edmonton, They told me to clean the air filter when it dusty otherwise it may affect the power. I am not sure what the actual reason is. Can somebody tell me the factors depending the power of a vehicle? If it is due to the dust in air filter. Please tell me the tips to clean it.