I have a 94 bonneville Vin L that is making alot of noise. I'm pretty sure that it is the exhaust system but not sure exactly what. The noise is coming from the exhaust manifold area. Would a cloged Cat also cause the noise to come from there because of back pressure? I can not visualy see any cracks in the exhaust but I cant get a good view of it. Is there some way to check to see where its coming from?

If you do a seafoam top clean smoke will come out of any leaks in the exhaust. Try moving your hand around the manifolds to feel any leaks. Be careful of how hot it gets. Check around where the manifold connects to the down pipe.

humm i do have a little seafoam left from when I added it to my gas and oil a while back. I will try that. I just didnt want to smoke up the block because I have picky neighbors that are a pain. Is it possible to add just a little and see what it does?

Just add a little and give that a try.

I had a crack in the down pipe that was just in front of the cat. $35 at a muffler shop and they spliced in a section.

I have a 94 SSE that required a new gasket and the clamp bolts them had to be replaced for the manifold bell shaped end that connects to the down pipe. The sound was like a hole in my muffler but I could tell it was coming from the front of the car. I left the car running, opened the hood and actually used a little bit of blue chalk for a chalk line and squeezed a little poof from the top behind the engine to see if a leak would blow the chalk powder in any direction other than down. Sure enough, it worked. Took it to a shop, told them what I thought was wrong, they called back and agreed. Within one hour my car was back to me in with the leak fixed and the car is as quiet as it'* ever been. Long story short, those gaskets can go bad and might need to be replaced otherwise you'll have a small exhaust leak causing a louder than normal exhaust.