Hey guys thanks for all help and theories offered.
I own a 2001 JDM Evo 7, purchased it second hand and been pampering her since day 1, trying to rectify all issues no matter how big or small.

I've been having this problem since I got the car.

Problem: when cruising at about 110-120 km/h, partial throttle just to maintain the steady speed, I get a fluttering/flapping noise. It's difficult to pinpoint the exact location of the sound but its def in the front, sounds kind of low. If I give it more throttle, the sound stops, if I back off the throttle a bit, it stops. It just seems to make the noise at the exact rpm/load I want to cruise at.

The car: when I first got it, it was stock except for a gutted cat and a reversed stock bpv. It made the noise with this configuration.
Now, I've fitted a GS ebcs (noisy bastard), Apexi Filter on MAF adapter, Blitz Touring Cat back exhaust and I've put the bpv on the proper way. It still makes the noise!

It's driving me nuts as I've been doing a lot of highway driving lately.
Thanks for reading if you've made it this far and I hope you guys can help.
Any questions just shoot!

 

Well I feel lonely

 

I think it's a Trinidad thing! I have the same noise on my Evo VI.

PM me on tuner, I will take you for a spin to hear it. BLUE_CP9A

 

I had the same annoying rattle thing. Suggest you pull your down pipe and cat, and shake them out. When I did I found a nut thatI remember dropping somewhere in the engine bay but could never find.

 

I get it, do you have a boost gauge in car? The selection of line you pass thru the firewall can be a bit noisy. The silicone vibrant I used tends to flutter about ~2-4 in/hg and goes away as soon as I reach 0, or let off

 

Ok, I'll ask the obvious question... Could it be BOV flutter?