Ok, so I’m driving normally, and all of a sudden my exhaust gets really loud and low pitched. I’m like, hey cool, my old stock exhaust sounds nice! Then I’m wondering just what happened…any ideas? The sound it makes isn’t really constant, it breaks sometimes, hard to notice. Its obviously coming from the rear driver side. Any clue what might have happened?
This is usually a sign that you have a leak somewhere, and in some cases your exhaust is ready to fall apart. Check for leaks at the connections, resonator, cat, and muffler. I had the same thing happen to me once, and about a week later I just pulled away from a light and it was LOUD. turned out it broke right after the manifold… tied it up with a dog leash (only thing I had with me) and got the middle section changed a few days later.
But you know, while it was disconnected, I could have scared away 5.0 mustangs… 
Yeah, i was thinking that would be it. I had a look at the piping at the rear of the car and its crazy rusted…Am I doing any harm by driving around like this until i get it fixed?
well it won’t damage your engine or anything… but the hole will keep getting bigger and if something breaks off, you can lose a chunk on the road, or it can hang down and drag…
it’s not like you can’t drive it until you get it fixed, but I wouldn’t wait too long if I were you…
I have seen very bad things happen to cars when the exhaust breaks. First small holes cause hot gass to exit in bad places under the car and can cause hot spots on the floor of the car. Not a reall big deal but can cause damage over long trips. THe big problem is if something breaks and a pipe hangs with the front hanging down. If it catches in a crack or hole it can turn into a spear and literaly rip itself completely off, punch holes in the floor of the car (not likely) or damage things like brake and fuel lines. Just check it out and make sure it isn’t going to fall off. THese things can do damage to cars behind you when your driving and they fall off. If it damages someone elses car you can be sited and have to claim it on insurance.
Thanks for all the info, got another question though
My car’s an auto, and ever since the problem with the exhaust its got weird behavior downshifting when letting off the gas. Like when slowing down to a stop, it’ll downshift abruptly and then the engine will rev a tiny bit for a second before going back down. Would this be from the exhaust, or some other problem?