I'm glad I am not the only one experiencing this! I personally do not think it is a rattle of something. If it was it would be more of a vibrating noise and would do it all the time (idle, etc) As for my intake, I put that rubber protecting piece around the hole to my fender that the pipe went through.
Could it possibly be something to do with the air going into the engine? (ie:new intake, new sound appears)