Strange noise/possible exhaust leak?

hey guys. So I have a 2007 Tacoma with the 2.7. Recently it's been making a strange sound, but only when it's revved over 3500. It sounds like compressed air being blown from a hose. It does it whether I'm driving or in neutral, but it's louder when accelerating harder than normal. Now I'm not a mechanic, so it might be, but I don't think it's an exhaust leak because under 3500rpm it never does it. It's also not a loose heat shield, as far as I can tell they are all tight.
Past that it sounds like its coming from underneath the passenger seat area.
So what might be causing this? Thanks guys

 

I have the same issue at the moment. IDK if you even still have this truck. Any leads?

Thanks

 

Need a soundbite or vid capturing the noise.
then I might have some pretty sweet guesses

 

I have the same noise. I also get it when I accelerate hard. it sounds like when the rear slider is open but louder.

 

Poster has not been here since the day he made the post. In 2016. Odds high you won't hear back from him. Suggest making your own thread on the topic.

 

See post #5