1998 Saturn SL2 Saturntech9

Loud noise coming from under the passenger side of the car. Appears to be an exhaust problem. Had the pipe welded January. Don't remember exactly what had to be done. Different sound then; like an exhaust manifold gasket leak. This sound is very loud, then quiets down. Seems to be louder at idle. Someone mention resonator pipe is a common problem with these cars. Where is it located? Don't see anything hanging down, however I haven't laid under the car to inspect. Low to the ground and only have stock jack. Any ideas? Thanks!