Well as you can see in my signature I own a Mazda 3, 2.3 I always felt the hot idle was slightly noisy and I found alot of people say "ticking is being caused by flaps in the variable air intake system" and can be fixed by replacing the manifolds? What!? This is not my Mazda 3, but it literally sounds 100% EXACTLY like this. I tried it on my own mazda and the "knocking" quieted down completely and sounded like new. Watch this video, he unplugged something and it stopped the "knocking" http://www.youtube.com/watch?v=_O8qSw4dxII Please whats your input on this?? & what could happen if I just leave it be?