First off, why do you want an aftermarket exhaust? Is it for looks, sound or performance? Each will determine what you should invest in, and all will differ in price.
A performance exhaust system gives you the best bang for your accessory buying buck because it appeals to so many of your senses. When you stomp on the gas and get pushed back against the seat, you can feel the increase in power. You can see the highly polished stainless steel tip and admire the way it complements your rides styling. And you get a deep, visceral feeling when you hear the exhaust note’s rumble that turns into a roar when you accelerate.
Performance exhausts range in variety. If you are driving a turbocharged car, a very popular first choice would be to invest in a downpipe, thereafter, include the catback which will then, in full, be a turbo-back exhaust system.
So what makes aftermarket exhaust systems one of the most popular performance upgrades among car enthusiasts? Like aftermarket headers, performance exhaust systems are built differently than their stock counterparts to reduce power-robbing restriction, promote exhaust scavenging, and ultimately free up more horsepower.
The first difference between a stock and aftermarket exhaust is the diameter of the pipes. The diameter ranges available on aftermarket exhaust systems vary depending on the application. However, these systems typically come with larger diameter options to flow larger volumes of air.
Again, the proper diameter size will depend on variables such as engine size, rpm, application. A respectable exhaust tuning shop sales rep can help you choose the right size for your specific vehicle.
Alternatively to having your exhaust custom made for your car, there are bolt-on exhaust systems available as well, however, you'll have to find the right kit for your car specifically. For example, if you own a Ford Fiesta ST, you can easily invest in COBB's pre-made performance exhaust system.
The second major difference between stock and aftermarket exhaust systems are the pipe bends. Stock exhaust pipes are typically formed using a technique called crush bending. Although crush bending is a quick, easy technique, it also causes performance-robbing restrictions at the pipe bends. To eliminate these restrictions, aftermarket exhaust manufacturers use a process called mandrel bending. This process utilises a flexible rod, which is inserted in the exhaust pipe. As the pipe is bent, this flexible rod prevents the pipe walls from collapsing or kinking.
The result is consistent pipe diameter with no restrictive kinks in the bends. Depending on your car and possibly other modifications, you'll maybe have to get your ECU re-mapped to gain the most out of your new system, and regrettably, to avoid a possible check engine light.
If your intention is to hear more of an exhaust tone, there are better ways to achieve this than others. You don't want to make your car sound bigger than what it is, nor do you want to jeopardise performance. A popular mod is installing a new muffler box which will result in a deeper, louder sound. Or to remove the catalytic converter completely (decat) this can result in slightly more power but you have no control over the sound it makes, and in some countries it is illegal for street use.
If you just want to have those shiny pipes to show off at car meets then it isn't always necessary to install a full exhaust system. A popular option would be just to replace your standard exhaust tips with aftermarket ones of your choice. This does not affect performance, nor does it greatly affect your standard exhaust tone either, but can aid in visual styling. These tips are usually very cheap, and any exhaust garage will install it within a few minutes for very little cost.