I remember I was working on my Yukon, changing the exhaust pipes myself. I wanted to see what it sounded like so when I started it up, the exhaust pipes fell right off. I took it down the street and I noticed it was a little bit louder than it have should of been. I got out and looked and the exhaust was gone! So I went back to my house and there they were laying there. I forgot to screw them in! I had them just attach by a small bolt where the holes were too put the screws in.