I think it's the blow off valve kinda sound at one certain point of the rpm range when you're pressing your gas. mine happens around 1100 rpm, both accelerating and decelerating.

 

hrmm...i don't get the whistle either...i think it's more of a 6th gen thing to get the whistle or anything similar. all the 5th gens i've heard only get the standard intake roar.

 

5th gen here

 

thats true. in my 4th gen even with my stock intake it has always made a kinda whitsle sound when im on the gas very lightly it almost sounds like turbo. its nothing wrong just that when the litle throttle body door is open a tiny bit rather than all the way it creates the whistle effect. just like those little nerf footballs and what not.

 

Alright guys, the whislte sound is natural. ITS SCIENCE!!! The whistle is the sound of the air and its velocity. Here's an experiment you can try at home:

1. Form your lips as if you are going to whistle
2. Now blow, and whistle
3. Keep your lips in the same position, but suck in air
Ah ha! So air can whislte when its being sucked in.

So the smallest change of path for the air being sucked into the car can affect the whistling. I have a generic short ram, and it doesn't whistle. But the slightest change in design or length can cause it to whistle.

 

i barely notice my intake sounds, my exhaust are F****** loud over that thing. But I can notice them nice sounds like a "Turbo" when I drive another car next to it (the driver is my gf)

 

I think its more of the throttle bodies between the F22 series and F23 series , besides ive also heard this whistle noise from V6 Accord and Nissan Maximas. Sucks to be Accord owner cause there isnt many aftermarket throttle body parts out there. I've seen some but i only recommend it with a built up H22a ..my .02 cents

 

Haha, I had this same exact problem long time ago. And people back then really didn't help me or agreed that they had the same noises. But here's a fix!

This is how I fixed my whistling around mid-RPM's like you noticed. For some reason, some Hondas experience this while others don't.

To fix the whistling, you have to adjust the idle speed in your throttle body. Turn it up for more air flow at idle. I'd say turn it about a turn to a turn and a half. That should do it. If it doesn't, turn it up some more. After doing this, the sound of my intake changed into a deeper roar and the sound near redline also changed to a deeper note as well. But the most important thing was that I didn't hear whistling anymore! And I think I got more power out of it.

So! TURN YOUR IDLE SPEED ADJUST SCREW ON YOUR THROTTLE BODY TO GET RID OF YOUR WHISTLING. Do this and report back to me because I haven't seen anyone else do this and tell me that it worked. But my friend suggested it because he does this when his friends get intakes to let more air in. Also after you confirm that the whistling is gone from the idle speed screw change, reset the ECU so that the engine will breathe better.

Another note: THIS ADJUST DID NOT RAISE MY IDLE RPM'S FOR STRANGE REASON. IT JUST MADE THE INTAKE NOISE CHANGE AND ELIMINATED THE WHISTLING. I hope I made that clear. Now see if this works!

 

I only get a roar with my Aem CaI, but my friend has a 2001 maxima with a CAI and he gets a whistle pretty much all the time..

 

I have a 99 four-banger. I couldn't get the "plug" out of my idle speed adjustment screw. Any ideas? Am I supposed to destroy the plug when I dig it out? It looks like they just shove some wax in there? I can't find anything to grab hold of to get it out of there. It ain't in a very convenient place either on my 4cyl. After I get that figured out, I'll make the adjustments and report back. Until then, still whistling!