05 wrx....... Ive recently started hearing a loud noise coming from the rear of the car. It sounds like something flapping in the wind .

The noise gets louder with the Higher RPM but the noise only is on when Braking or Lifting the foot off the accelerator and coasting kind of thing.

The higher the engine speed the louder the sound.

Any ideas????

Only recently noticed it since removing the back seats exposing the chasis. Not sure if it would be something to do with that.

 

no noise on idle or whilst accelerating, its while decellerating if thats a word.

 

Put your seats back in, more than likely just the road noise that you would not normally hear.

 

Humidity & air circulation vents sitting either side lower rear arch behind bumper sides , they have 1 way flaps wich blow in the volume of air passing ( at speed) only noticeable with rear of car exposed
That's my guess anyway