I was just wondering how mufflers work. I need the informaton to make the best decision possible for my car

Exhaust noise is actually the hot gasses expanding, a muffler slows the gas flow and also cools it as well, a good muffler has pipes and baffles that change the direction of the gas flow and it allows it to expand with in the muffler as well, that is why they are bulky, so basically they slow and cool the exhaust gas flow.

Imagine talking with another person face to face. Now imagine that other person in another room, in a closet, with the door mostly closed. Carrying on a conversation would be harder because you wouldn't be able to hear 'em.

The exhaust pulses from an engine start out really loud but the shock waves go through one third of the muffler, through a small opening into another room, to the other end of that room, then through another opening into a third room, to the other end of that room, then out the tail pipe. That's like sitting in a closet in your house and trying to talk with someone standing outside, ... In the garage, ... With the doors closed.