One problem related to manifold/header/muffler/tail pipe has been reported for the 2004 Cadillac STS. The most recently reported issues are listed below.
I was standing at the back of the vehicle (Cadillac srx) and I leaned against the back bumper with my leg, and burned my leg on the tailpipe. I was standing "flush" with the bumper, and it burned my leg because it sticks out too far (about 1/2 inch too far) from the bumper. This is the second burn that my family has experienced; one month ago my 7 year old son burned his leg on the tailpipe as well. His burn was much worse - it blistered and bled and scabbed over. He was climbing into the back of the vehicle to retrieve an item from the trunk. I believe that Cadillac needs to fix the tailpipes on the car by either shortening them by 3/4" or 1 inch, or by extending the bumper somehow. This is a design error, and a safety issue! I want Cadillac to take care of this before one of my younger kids, or someone else is burned. Cadillac has told me there is nothing that they can do, and I do not find this acceptable!.