I'd be checking the exhaust system hanger's if the rattle occurs under hard cornering, or max acceleration (engine mounts allow the engine to move an awful lot under hard acceleration or abrupt full throttle to zero throttle expereicend when pushing the envelope), and as such, the exhaust will move about quite a bit ....
If nothing has fallen off, I'd be pressing on until something does, then you will know where it came from !!
