Yes, the little one near the exhaust manifold is called a light off converter. It heats up very quickly after the engine is started to decrease emissions during the warm up period.
Yes, this does have emissions ramifications, however, WITHOUT the converter, you emit hydrocarbons, WITH the converter you emit sulpher(sp?) This is six of one and a half dozen of the other. The biggest environmental advantage to the converter was that when it came out in 1975, it forced everyone to move away from leaded fuel. Otherwise the catalytic converter was just another hoax put over on us by the infinitely wise US Congress. You know, anyone who is elected to congress is automatically an expert on any subject in the world.
Have a great day,