Your scenario is much like mine and it's perfectly normal. No need to stress...

 

i just tell my friends its called a "turbonator" you know those thing you put in the intake to make air swirl to increase gas mileage and give you 50+ rwhp

 

I posted a comment in a thread not too long ago about this because someone else inquired. Yes it is normal. It is coming from the intake. Pop you hood, turn the engine on and twist the throttle, you will hear it clearly from the intake. Even get closer to it and listen.
Don't worry about it though, there are many S' that do this. From what I understand, this is a charactoristic of Honda's high rev engines caused by the intake valves.

 

Those are just your guys turbo's