Manifold/header/muffler/tail Pipe problems of the 1998 Nissan Sentra

My car lost power,I had to drive maybe (6) six miles to the dealer. Went I got there I got out and noticed that there was smoke coming form trunk. I open trunk and saw that the carpet was smoking and had melted. There was a burnt spot where the carpet was. My point is that I had three quarter tank of gas in my car. I could have been blown-up in that car if I had to go much farther. It really burnt that carpet good. The cause of the problem was that it was the exhaust manifold and the converter,which comes together and cost $901. 87 to repair. I bought this car only a week prior to the incident,from the Nissan dealership on hwy 70 east no dought.