I am new to this site and any advice will be greatly appreciated. I have a 2004 4Runner Sport with a V8 that is bone stock with about 110 K miles. I bought it used about 2 years ago and have had no problems. Yesterday on a trip, after driving for about an hour, I was going up a slight incline when all of a sudden it sounded like a bomb went off under the truck. It was the muffler. It literally exploded. The truck still ran fine after that. Anybody know what would cause this to happen?