Originally Posted by Dameon
Mine was a broken baffle in the right side muffler. I got a whole new exhaust, converters all the way back.
I had the exact same issue. My new exhaust was installed yesterday and it's working great.
I asked the dealer if I could apply the difference toward the purchase of a GM Performance Exhaust and they said GM said no, it has to be an exact OEM replacement part. Oh well, the rattling is gone and thats good.