21337R

^^ Yep that is the signature Honda whistle. My B16A did the same exact thing. Its kinda funny because if you shift just right it sounds like a mini blow off, lol, I have had people ask if it was turbo because of that noise. One other thing worth mentioning is that I have heard aftermarket clutches (ACT in this case) that made a very similar sound when being slipped.

Ks320

Same here

You aren't the only one

PrimoGen

its probably the secondary air pump/intake <--- whatever it is called

offroad2000

I was gonna search for that. Mine's all stock and does it as well. I was thinking belt or something. Good to know it's normal.

s2kmugen

my AEM intake use to do the whistle too. too bad my J's doesnt

Vik2000

I had this hissing sound too and was worried, but then discovered that it was not a problem. I just tell my friend it's my supercharger charging up. (I have no sc)

Moddiction

Yeah for some reason I just didn't notice it until my friend pointed it out to me and got me worrying slightly. But I have started to notice this car can make some strange noises that are normal.

DougEFresh

mine only makes the noise if i pass a hot chick. hahahaha, its completely normal and harmless.

Moddiction

Just went for a drive again and the sound mine is making sounds a little more like a cricket high pitched chirp. Sounds like it might not be air but a kinda scrape high pitched noise. Still does go away once revved up a little bit though.
It also really sounds like it is coming from the right front side of the car.

S2k Dude

Makes sense that it is probably the throttle body. I've had two S2000's and both have made the same whistling/ringing sound under light throttle at about 3000-3200 RPM. I also heard the same noise on my '87, '89 Civics and '96 Prelude but not on my wife's '04 CR-V.