its a beautiful sound if i must say so

 

one of the main reasons i bought my sri (first mod ) was that whistle sound. Ih eard it in my friends civic and fell in love

sadly mine does not make a whistle sound at all, it makes high pitched noises when sucking in air though that kind of sounds cool, like a turbo. Its on an o4 civic that has the throttle body pointed up, and its 2 pipes and a aem filter

(aem sri 160$)
I can def tell the difference but only when revving my rpm higher, it makes my car sound hella aggresive. But now i got a magnaflow catback so i cant really tell if i hear my intake, plus i blast my music too ><

 

I would go with the AEM intake. A while back I bought an intake kitfrom e-bay and it made that annoying whistling sound. On my accord I have a Typhoon Intake K&N. I took off the filter and tried it onthe pipe that was on my Si at that moment (ebay intake pipe)and it also made that stupid sound!!!!I just decided to get an AEM intake and it made a heck of a difference. I guess it was making that stupid sound because it's all on the PIPE how it's bend and thickness too.
YOU get what you pay for!! AEM or Injen or the Typhoon K&N intakes

 

when i first installed my K&N typhoon sri i noticed that whistling sound also, but i only heard it at take off and at low rpm's. originally i thought something was wrong but no sensors were lighting up. the only reason i found itstrange is bc my last car had a weapron r sri w/ a K&N replacement filter. no whistling sound. i agree with previous posts, yes the filter is very vital part, but the tubing is also important. price differences differ due to color, material, and size or number of chambers (ie: aem v2). personally, im very happy w/ my K&N sri.

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04 civic lx sedan
K&N Tyohoonsri
Neuspeed frt upper strut tower bar
NGK Iridium spark plugs
Tanabe/sustec DF210 springs
PIAA Xtreme white plus headlamps

 

honestly i cant see it making a huge difference switching the whole intake, but putting a good filter on it will do at least something. i would stick with your intake and spend the money elsewhere.