The catalytic converter does a bit more than that:

How Catalytic Converters Reduce Pollution
Most modern cars are equipped with three-way catalytic converters. "Three-way" refers to the three regulated emissions it helps to reduce -- carbon monoxide, VOCs and NOx molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required (they are very expensive).

The Reduction Catalyst
The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2.

The Oxidization Catalyst
The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas.

The Control System
The third stage is a control system that monitors the exhaust stream, and uses this information to control the fuel injection system. There is an oxygen sensor mounted upstream of the catalytic converter, meaning it is closer to the engine than the converter is. This sensor tells the engine computer how much oxygen is in the exhaust. The engine computer can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the engine computer to make sure that the engine is running at close to the stoichiometric point, and also to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO.

 

all you should have to do is a 02 sim, (if you need it) it won't hurt it, but it may be a lil louder

 

they smell bad. the exhaust is black (remember im talkin about the exhaust) it lays down a smokescreen like that F350 in that track run, and the cat will change the sound of your exhaust.

but yeah...anything that makes your car breathe easier will increce your gas milage

 

its a 95, so it doesnt have an o2 sensor after the cat. so hes lucky in that way, i put a magnaflow system on and i just cut em with a grinder and then used an air hammer to get the studs out.

 

Dosn't all exhaust smell bad? The only exhaust smell I like is from race gas!

 

I guess we shoulda put "smell worse" rather than "smell bad". Sorry.

 

Ok.. lets go over this again. No car I own has a catalytic converter. None of them smell bad. None of them smoke, except my civic a very tiny bit, and only when I go WOT, and thats b/c Im burning a little bit of oil. And my civic and dads 350 truck in no way even sound bad. In fact I think it lowered the pitch of my civic, which is a very good thing. It increased HP and Gas mileage.
Now I dont know where you are copying/pasting your information from, but I can go out and drive behind my dads truck and see first hand that he does not "Lay down a smoke screen".

And negotiator, I was giving him the short version

 

Fair enough, but just to let you know, it doesn't go through carbon, it's usually platinum. (no carbon in a cat)

 

Here:

http://auto.howstuffworks.com/catalytic-converter.htm

This has animations and what not.

 

That's where I got my info, but I thought I'd bring it to you rather than make anyone work for it.