I noticed this weird sizzling sound two days ago when I replaced my bypass hose from a leak. What the hell can it be? Doesn't sound normal. No overheating issues from what I noticed.

Just my luck :/

Here is a video http://www.youtube.com/watch?v=_edijcaGHNU

 

On my gsr, when I turn off, I can hear the air pressure suck or release through the air filter a moment after the engine stops turning.
Can't really hear what yours sound like exactly.

 

Mine is coming more towards the thermostat area/ passenger side. And it's not the air filter. I've heard that sound before on my ef when I had a aftermarket intake.

 

Normal.