95 SC2 Slight Knock

I've got a 95 Saturn SC2, with 118,000 miles. She runs great, starts every time. The only thing is that I noticed her gettin a lil loud, which I'm pretty sure is exaust. But also, theres a slight knocking sound, what do you think it could be? I'm also pretty sure the cat needs to be replaced as most the exaust noice is coming from up front.

When is the last time you changed the oil, and checked the oil level?

Also can you give more details about the knocking, can you tell where its coming from, or what you do to make the sound louder or quieter.

Does it knock after the car is shut off?

need more info on this. #1 thing to do is, CHECK THE OIL! saturns typically burn oil without notice (might be reason for needing exhaust) which is the main reason why most engines go. when you bring up the rpms, does the knock get worse? do you really only hear it at idle? try and narrow the noise down to certain area, you will have to listen very closely to it varying in different spots, say listen to the oil pan then valve cover then timing cover, just go around like that till you find where it seems to be a bit more loud at.