Modifying your exhaust can be inexpensive but costs can mount quickly the more changes you make. The entire exhaust system includes two exhaust manifolds (headers), two catalytic converters, two pipes, two mufflers and finally the exhaust tips. Any and all of these parts can be replaced or removed with varying degrees of power increase and changes in sound (both loudness and tonal quality). There are essentially two ways to go about modifying your exhaust system; first, just cat-back (which means changing everything after the catalytic converters) and second, headers and cat-back. However, it is possible to remove and replace any individual part, the aforementioned two are the most common.
If you’re going just going to be driving in town and on the highways, then cat-back is probably enough. Replacing the headers adds considerable time and cost to the project. It will also increase power gains, but is only really effective if you’re making major engine modifications that necessitate an exhaust system with greater flow and efficiency. If intake and exhaust is all you’re interested in, then the stock headers are probably enough.
Another possible modification if only going cat-back is the addition of an X-pipe, which helps balance the back pressure like the stock H pipe and also scavenges the exhaust to help the engine breathe a bit better. Unfortunately, exhaust modifications are usually a poor project for the novice DIY’er as welding is required. For proper results, it’s often best to find a reputable shop and have them do the work.
What are the negatives? Well, modifying the exhaust makes your car louder (which is the reason most people do it) and obviously it will require you to spend money. This is a poor place to begin if you’re looking for power gains, unless you’re building a monster engine in which case you’ll have to modify the exhaust. But if you want 50 hp, this is not the way to do it.
As an enhanced sound is what most people are after, following are videos (in alphabetical order) of the most popular exhaust systems so you can hear what they sound like.
First off, Billy Boat: