Hear rattling noise when accerarating on 2005 Mitsubishi Galant

Problem occurs while accerarating and gets better at speed of fifty but noise can still be heard slightly.

Asked by for the 2005 Mitsubishi Galant
Is the rattle starts right away when you crank the engine?
I'd get the catalytic converters checked first, than the rest of the exhaust system, including all the heat-shields.