SOME VEHICLES MAY EXHIBIT AN UNUSUAL RATTLE/BUZZING TYPE NOISE FROM THE PRESILENCER WHEN DRIVING AT APPROXIMATELY 1800 RPM. THE LOWER (REAR-SIDE) OF THE PRE-SILENCER MAY BE THERMALLY DEFORMED DUE TO INSUFFICIENT RIGIDITY (FEWER WELD SPOTS). THE DEFORMED PORTION MAY RESONATE EXHAUST GAS PULSATIONS, WHICH CAUSES NOISE. A REINFORCED PLATE HAS BEEN ADDED TO THE PRE-SILENCER TO INCREASE THE RIGIDITY, THEREBY ELIMINATING DEFORMATION.