1998 Saturn SL2 Themostat

Yep. Resonator pipe. Will do!

OK. The car is now making a new noise. It seems to be coming from under the passenger side of the car. I believe it's part of the exhaust system. I don't believe it's the muffler. You had mentioned something called a resonator pipe. Back in January, the same part of the car had to be welled. Was loud, like the exhaust manifold gasket. This sounds more like something loose. Gets real loud then quite. Seems loudest at idle. The piping was checked by the inspector who failed it until the welding was completed, January. Have you had any experiences with something like this? Is this where the Resonator pipe is located? I don't see anything hanging down. Haven't crawled under the car yet to look. Thanks!