Just need some help regarding my exhaust.

So I was driving home from class, right after a huge storm. I was traveling down a road to get home, and out of nowhere I drive right through a huge patch of water. I'd say a patch about 1 foot deep and 15 feet long. The sewer drain backed up, and water filled up the road. It was impossible to see, and doesn't look like a deep patch of water when your not in it. My car is running great, but I think I may have ruined my exhaust.

About a half a day later, on my way home from my parents, I start my car up, and "VRRRRROOOOOM", from the exhaust. What used to be quiet, is now loud. It sounds like I have some crappy exhaust on my car now. It's loud and annoying. There is no exhaust leak, but just loud exhaust from muffler. So what would you say is bad? The catalytic converter or the muffler itself? Once again, it used to be very quiet, and now its nowhere near quiet.

are you sure the water didnt pull something apart?
another thing is maybe something inside the muffler broke...well I guess that would be baffles huh??? lol

You can seafoam the car and see where the leak is coming from if there is one, or you can just take it to a muffler shop where they do free inspections to figure out what's up. Exhaust heat+cold water=fail.

my guess is it broke in between the muffler and the last flange.... look by your right rear spring and see if its disconnected.