Noise from turbo or air filter

Hi, I have fitted a race-chip to my car which I have had no problems with for the last five or so months, but a little more recently around two months ago I fitted a cone air filter which allows more air into the engine. At first I had no problems with it but after the cold weather kicked in when I am driving and I change gear between two and three thousand revs as I take my foot off the gas I get a really horrible sound kind of metallic, I usually get a sort of whoosh sound but it is that sound combined with a metallic sound really hard to describe. It does not happen every time only sometimes and only happens at this rev range. I have no idea what it could be. I have checked all connections around the air filter to check if they are tight and they are. Do you have any idea what it could be? Thanks