I just finished installing a K&N cold air intake on my 2006 S2000. During the install everything was double checked for tightness and no parts are loose. After the test drive, I heard a strange sound when the engine shut off. It sounded as if it were coming from the throttle body, like it was snapping shut. I have driven a 2005 S2000 with a K&N CAI, and this sound did not occur when the engine shut off. Has anyone else experienced this? The car runs great, but I

 

Your car is very different from a 2005.

 

sounds normal, its the air filter suckin in air right when u shut it off.

 

^^^ exactly what i was thinking the sound was. I hear it with my k & n aswell.