Hello all. New here. Need some help with a rattle. I installed a MBRP Cat Back exhaust to the stock cat on my 04 TJ. The rattle occurs only when accelerating in drive and stops as soon as I let off of the gas. At first I thought it was the fan hitting the fan shroud but have ruled this out by installing a 1' BL and MML. The install of the exhaust was a tight fit. I have checked all of the hangers and pipe. Everything is free and clear of hitting something else. Could this be a bad cat or something else? Any help would be much appreciated. I've spent hours looking for the issue and am stumped. Edit: Thought I'd list more info for the peekers in the hopes someone will have an idea. If I put the Jeep in drive and lightly give her gas, not rattle/knocking. As I pick up speed, the rattle knock starts and the faster I go, the faster the noise.