 Welcome to another episode of Cobb U. Today's episode is a special one because it marks the end of our journey through the engine. We've managed to follow air through the intake, into the combustion chamber, and now it's time for that spent air fuel mixture to leave its home. Now, ironically, the exhaust is the last component connected to our engine, but it's one of the first things an enthusiast might change when they get their car, because swapping components can change the sound, improve performance, and make the rear end of the car look a little better too. To get a better understanding of what's going on, let's take a look at the components that make up the exhaust system and how they all work together. Now, for the sake of today's demonstration, we'll be using components from a Subaru WRX STI, so some of the components may or may not apply to your application. Also, for those of you with naturally aspirated engines, the only difference is that the gases from the exhaust manifold are going to go directly into a catted section instead of a turbo. So keep that in mind as we go along. The exhaust system is made up of an exhaust manifold also referred to as a header, an up pipe, a down pipe, a mid pipe, and a muffler and tail pipe. The exhaust manifold connects to the head, and gases enter through the inlets here and here and exit through the outlet here. The up pipe connects to the turbine inlet of our turbo and is unique to some Subaru motors due to the location of the turbo in relation to the exhaust manifold. Next, we have a down pipe, which connects to the opposite side of the turbo and includes a catalytic converter. We also have a mid pipe, which can be resonated or non-resonated to help control the sound of the exhaust, and finally, a muffler and tail pipe to help control the volume of the exhaust or how loud it gets. When talking about exhausts, you're generally going to hear one of three setups, turbo back, cap back, and axle back. A turbo back refers to an exhaust that is modified from the turbo all the way back to the tail pipe. A cap back is only modified from the end of the catalytic converter back to the tail pipe, and an axle back is from the axle back to the tail pipe. Now that we know the components that make up our exhaust, how do they all work? After the combustion process, the exhaust gases make their way out of the exhaust manifold under pressure and either enter the turbo directly or, like in our Subaru motor, through an uppipe first and then the turbo. Once the exhaust gases pass through the turbine or hot side of the turbo, they enter the downpipe. Our downpipe has a catalytic converter, which reduces emissions that are a natural byproduct of the combustion cycle. After our exhaust gases have made it through that gauntlet, they're onto the home stretch. The exhaust gases then pass through a midpipe, which contain a resonator to help give your exhaust its signature sound. And last, they pass through the muffler, which helps control the volume of your exhaust and exit through the tailpipe. The exhaust system's components are pretty straightforward, but there's a lot of things to consider. You can't just go all willy nilly and hack off your exhaust and be all straight pipe, bro. Which leads me to... It's easy to lose sight of those commandments from time to time, but when all is said and done, all we really need to do is exercise some common sense when choosing our exhaust components. Let's go over each of those commandments so we get a better understanding of what they really mean. A catalytic converter helps curb greenhouse gases. So if your car sees any time on the road, there's no reason that you should be running without one. It's a common misconception among some enthusiasts that any restriction to the exhaust is a bad one. And as a result, some people feel that they won't achieve their power goals if they run a high-flow catalytic converter, which nothing could be further from the truth. Anyone with some stainless, a welder, and fabrication skills can make an exhaust, but how's it gonna fit, sound, look, and even perform? When engineering the performance and sound characteristics of each exhaust system, there are countless tweaks and iterations that it goes through before it hits production phase. So slapping a few pipes together and calling it a day just isn't gonna cut it. We want the rear end of our car to look just as good as everything else, so we shouldn't cut corners when it comes to our exhaust system. Now, some people will just upgrade the rear section of their exhaust from the axle back. And this will upgrade looks and sound, but not much else. If you want to do more than just looks and sound, you're gonna need to upgrade the entire system. This is something we've discussed regarding the other components of the engine, and this is no different. Any time we're upgrading components to the exhaust, we need to take a step back and make sure we're running the proper tune to the ECU. Some modifications, like an upgraded cat-back, may not need to be accounted for in the calibration if it doesn't affect the tune in a significant way. While an upgraded downpipe with a high-flowing catalytic converter definitely needs a new tune. Not only to make sure that your car runs properly, but also to make sure that you're getting the most out of the modification you just performed. The commandments are meant to be followed, but each scenario is different. If you're unsure of how the commandments affect your car and its setup, you can contact a local Cobb pro-teener or call our customer support team. We'll get you headed in the right direction. Lastly, when doing this type of part install, you will generally use these kinds of tools. Ratchets, sockets, and extensions. Penetrating oil. And exhaust hanger pliers. And now it's time for the pro tip of the day. Riddle me this. What part of your exhaust system never comes in contact with exhaust gases? Answer? Exhaust hangers. Your exhaust literally hangs underneath your car and is held up by these hangers. It's a commonly overlooked component, however, it's one that you should consider upgrading, especially if you plan on driving your car in a manner that has the exhaust moving around quite a bit. Like taking it to the racetrack or maybe your car has a ton of miles under its belt and the hangers are looking a bit toasty. They're inexpensive, easy to install, and they make a huge improvement when trying to keep the exhaust from swinging around underneath your car. Okay, one last thing before we go. We've talked about how a modified exhaust can change the sound. Well, crank up your speakers because we've got some examples of some really cool exhaust sounds. And with that, we complete our journey through the engine. And now we can start exploring other systems around the car, beginning with our next episode where we'll discuss engine cooling. Thanks for joining us and be sure to subscribe to our YouTube channel so you can check out future videos. I'm Emmy, your host for Cobb U. Remember, check out Cobbtuning.com for all your parts and tuning needs. Do you like the storage solutions featured in our studio? Then visit SonicToolsUSA.com to get more detailed product information.