Exhaust leak?
 

I've had my car over a year now, and this noise has been coming from under the passenger side dash underneath the car. Anytime I'm accelerating hard, or even getting onto a freeway, I hear this fluttering noise coming from there. My guess is that the mid-pipe on the passenger side is not synced up very well with the stock headers. Hasn't caused any problems, but it is a bit annoying.

I tried to record a video, but the Borlas just eat it up on the camera haha. Any ideas? Thanks MF!