Noise at 2500 rpm.

[Bleach2K9]

Hi all,
I have a 2009 coupe lx with about 6k kms, really new. And recently I have started hearing a noise when downshifting that starts at exactly 2500 rpm's in every gear. I was reluctant to post because I'm not sure how to spell the noise lol, ... it's like an RRRRRRRrrrrrr that follows the tone of the engine, it does not make the sound when the clutch is in, or when I excel... I'll give you an example.
Lets say I'm 3rd and I'm slowing and the rpms are dropping, as soon as it hits 2500 RRRrrrr then I down shift to 2nd and as soon as it hits 2500 RRRRrrrr.
The only mod that I have on the car is a K&N sri, I't can be the problem I put it on two months ago and this started happening last week.

Any ideas ?
Thanks in advance !