So I installed a K&N CAI and now I hear a clicking sound when accelerating. The sound is only present under a medium light to medium steady acceleration. When I put the pedal to the floor I don't hear it. The sound is fairly steady, and I would estimate 3-4 clicks per second. Is this normal noise from the engine that I couldn't hear when the factory box was on? My friend has an 04 impala and he has a K&N and it makes the same noise, but it is less pronounced. Thank you for your time and help.