Well......its been a little while since I mentioned this problem and just recently did a quick check on it. I changed the oil while the car was on a lift. I took a synthetic hammer and tapped on various parts from the exhaust minold to the cat......my ears aren't the best in the world, but I didn't hear a thing. If something was in the block.....wouldn't the noise get progrssively worse or louder? Btw, I'm going to get a header as an excuse to really see if it was the piping. I'm not gonna beat on the stock header as hard as I can to see if it rattles.