catalytic converter Q

i know the cat. reduces emitions but does it affect the sound at all?

Yes, it has a small muffling effect. It muffles about half as much as a good muffler would.

It affects the sound a great deal. With cat and muffler exhaust is nice and quiet, with cat and no muffler exhaust is quite a bit louder, with muffler and no cat exhaust is between stock and without muffler but not much louder than stock setup, with nothing just straight piped it's extremely loud almost to the point of a nascar exhaust.

so if you wanted to make a sleeper could you put 2 cats on or 2 mufflers? i mean just so it is real quiet

Yes at the risk of restricting exhaust flow to the point where your power suffers considerably.

Use good quiet mufflers, use a crossover pipe (H or X), and add resonators. Resonators are basically extra mufflers that use sound deadening material in a free-flow design to further cancel noise.

Some people use race "bullet" mufflers as resonators with good success.