Aftermarket Exhaust System – For Improved Overall Performance

Exhaust System Image

There are many aftermarket improvements you can make to better your car’s performance. Most of them focus on the “front end” of the car. This includes cold air intakes, turbocharger and supercharger systems, and upgraded internal engine components.

What we’ll be covering in this article:

Where Is All That Power Supposed To Go?

Let’s now focus on the “back end” of your vehicle’s power production system, the exhaust system. What happens on the far side of your engine’s exhaust valves is very important to your car’s ultimate power output. If you have put a lot of time, work and money into increasing your engine’s output, but you still have the stock exhaust system, you have not done the entire job.

It’s like your engine is inhaling through a large pipe, but exhaling through a straw – not a good combination!

Your exhaust system is an essential piece of your car’s power production system. By getting those spent exhaust gases out of your engine faster and more efficiently, you make more power. This is how an aftermarket performance exhaust system can make the most of all your “front end” modifications. Here we go…

Let’s take a deep dive into all components of a performance exhaust system that will make the most of your “front end” upgrades.

Catalytic Converters – You Need To Keep Them

Catalytic Converter Image

We should start the discussion by accepting the nature of today’s highly regulated automotive world. Your car’s emissions control system is highly sophisticated, computer-controlled and totally integrated into the vehicle.

More and more states and localities are requiring smog tests at regular intervals – if you can’t pass the test, you can’t drive your car. This system must be retained when you make modifications to your exhaust system. For our purposes here, that means the catalytic converters must stay as part of your exhaust system.

The good news is that to survive, aftermarket exhaust system suppliers have learned to adapt to these regulations. The result is a wide variety of systems that are legal in all 50 states, work with your converters, and have all the necessary emissions system connectors needed.

Let’s first take a look at the two most important exhaust system items. These are the components that connect to the front and the back of your must-be-kept catalytic converters: performance exhaust headers and upgraded cat-back exhaust systems.

Performance Headers – The First Piece Of The Puzzle

Exhaust System Header Image

The exhaust headers that were installed on your car at the factory are not made to improve performance. They are the result of many compromises demanded by the cost accountants and the emissions system engineers.

They are made as inexpensively as possible to make the accountants happy, and they have a primary goal of warming up your catalytic converters quickly to make the engineers happy. Performance is simply not a consideration.

Then we have performance exhaust headers, which are specially designed to get the high volumes of exhaust gases produced by your front-of-the-engine upgrades out of the cylinders as quickly as possible. Depending on their design, these headers can add horsepower and torque, help engine breathing, reduce operating temperatures, and even improve fuel economy.

For example, if you have an inline four-cylinder engine or a V-8 (which is like two inline fours), your headers could be either a 4-2-1 design or a 4-1 design.

  • A 4-2-1 header design has the four pipes coming out of the cylinders merging into two pipes, and then into one before continuing on to the catalytic converters and the exhaust pipe. This design will boost your power across the rev band, with the highest output increases in the low and middle ranges.
  • A 4-1 header design takes all four pipes and merges them into a single “collector” which leads into a single outlet pipe. The 4-1 design of this header maximizes your power at the top end. Think about your driving profile and what your car’s performance would benefit most from and choose accordingly.

Scavenging For More Power

Exhaust headers that are well designed and optimized for the type of performance driving you plan to do can also increase your engine’s output, through a process known as scavenging. As the exhaust gases leave the cylinders, they create high-pressure compression waves that help to push the gases through the headers.

But while this is happening, there are also weaker negative pressure waves which travel back up the header pipes toward the exhaust ports and the combustion chambers.

The negative pressure creates a vacuum on the exhaust side that can actually pull more air-fuel mixture into the cylinders (if both the intake and exhaust valves are open a the same time), thus increasing power! Scavenging benefits performance in three ways:

  1. It helps exhaust gases to flow out of the engine better
  2. It pulls the incoming air-fuel into the cylinders
  3. It helps to empty the cylinders of exhaust gases

Make Sure You Get Mandrel Bent

In terms of construction, look for performance headers that are mandrel bent. This assures that where the header pipes curve you get smooth, constant radius bends that let the exhaust flow smoothly without obstructing or constricting it. Some designs have equal length pipes running from each cylinder to where they meet at the collector, for optimum performance.

Selecting The Right Headers For Your Car

Two recommended sources for both exhaust headers and cat-back exhaust systems are autoanything.com and amazon.com. They both have a large selection that will fit many cars. You can search for exhaust headers for your make and model. Do your research thoroughly – check customer reviews to see how purchasers liked their header purchase, and contact the sellers if you have any questions you need answers to.

For Extra Support, Check The Owner Forums

Another great way to research the right headers for your car is to look on internet car owners forums. These are communities focused on a single brand or model, where you can benefit from the experiences of a large group of owners of the same car you have! Search for these forums by make and model, then search within them for exhaust headers and systems comments.

This is an excellent source of feedback that should steer you in the right direction and keep you from making a poor decision.

Next Step: Cat-Back Exhaust Systems

Exactly as the name suggests, cat-back exhaust systems connect to the back of the catalytic converter(s). They come with all the pieces needed to get your exhaust gases from the headers and converter to where they exit the rear of the vehicle. These systems usually include pipes, mufflers and exhaust tips.

Performance cat-back exhaust systems provide you with several benefits compared to the stock system. They are far less restrictive, due to their use of larger diameter piping that is more gradually curved (mandrel-bent is better!) and mufflers that flow more freely. The improved quality of the exhaust sound that you get is an added extra benefit!

X-Pipes And H-Pipes

If you have a V-type engine like a V8 or V6, with an exhaust stream coming from each bank of cylinders, you may notice that some exhaust systems have a design where the dual exhausts merge or connect to each other. These connectors are called X-pipes and Y-pipes, depending on their design.

H-Pipes

The H-pipe came first. A simple piece of right-angled pipe that connects the dual exhausts to each other, it was initially developed to quiet the exhausts on high-performance V8 engines. By allowing the exhaust pulses to exit through both sides of the system, exhaust noise was noticeably reduced.

Later it was discovered that the H-pipe also increased power in the low and medium-speed ranges by reducing exhaust backpressure. This benefit went away at high rpms, though, because the exhaust gases were going too fast to make the 90-degree turn it takes to flow through the H-pipe. This led to the development of…

X-Pipes

The X-pipe evolved from the H-pipe, improving on some of the H-pipe’s shortcomings. Instead of using a right-angled connector like the H-pipe, the X-pipe smoothly merges both sides of the dual exhaust system. This results in improved power throughout the rev range due to the fully equalized exhaust pressure that the X-pipe brings.

This design is ideal for high-revving OHC V-type engines, while the traditional H-pipe works best for big-block V-8s that develop their power at the lower end of rev range.

Thinking About Materials

Performance headers and cat-back exhaust systems are available in a variety of different materials. What is the best choice for you?

There are two factors to consider when choosing materials. One is your budget. Solid stainless steel is the longest lasting material – and the most expensive! Your less costly options are ceramic-coated steel, aluminized steel and painted steel.

The other factor to be aware of is where you live and how you use your car. If you live in the snow belt and will be driving your car through all four seasons, consider investing in stainless steel, especially if you plan to keep the car a long time.

The stresses of going through many winters takes a toll on your exhaust system, particularly if you are in an area where winter storms mean heavy use of corrosive road salt. If stainless steel is not in your budget, ceramic-coated steel is the next best choice and should be more affordable.

If, on the other hand, you live in a mild climate where the temperature usually stays above freezing, you can get away with less-expensive materials and do your budget a favor!

Shopping For Cat-Back Exhaust Systems

Shop online for your next exhaust system

Again, check out autoanything.com and amazon.com. These two recommended sources have a great selection of cat-back systems. Search by make and model and don’t skimp on the research! Customer reviews will give you insights into other buyers’ experiences with the products. Don’t be afraid to get in touch with the sellers and ask them questions about their products. Make sure you get the right product for your car and your needs!

Upgrade To High Performance Catalytic Converters?

Catalytic converters are one more element of your exhaust system that can be upgraded. These are available from many exhaust system manufacturers, whose better-flowing converters are designed to their systems perfectly. High-flow converters like these work with the other parts of a performance aftermarket system to maximize power.

Going The Component Route

Maybe you don’t need a complete new system. You may have a performance car with a decent stock exhaust system that you’d like to improve, or maybe a whole new system is simply not possible budget-wise. Let’s go through the options you have in this area.

Performance Mufflers For Better Flow

The single best component upgrade to an existing exhaust system is an aftermarket performance muffler. Performance mufflers are less restrictive than stock mufflers and sound way better. Again, construction materials will vary, so balance your climate’s demands and your budget on this issue.

Look for a performance muffler that is the same approximate size as your stock muffler, so that fit will not be an issue. Next, make sure that the inlet and outlet pipes match your existing setup. The inlet pipe may be in the center or offset to one side, the outlet pipes can be centered, offset, or even dual, depending on how your car’s exhaust system is designed.

Exhaust Tips – Your Car’s Exhaust Jewelry!

The final touch to your exhaust system is a distinctive exhaust tip. Available in a wide variety of materials, finishes and prices, this cool appearance item will dress up the rear of your car, even if it is the only exhaust modification you make! You can get angled, rolled, turndown, single or dual outlets. Check out autoanything.com and amazon.com for a great selection.

California Residents Alert!

If your car is registered in California, make sure that your exhaust system is CARB (California Air Resources Board) certified. Visit http://www.autoanything.com/air-intakes/what-is-carb-exempt for more details on selecting the right parts to keep your car smog legal. This is no joke.

Getting The Most From Your Upgraded Exhaust System

Once you have installed your new aftermarket performance exhaust system, drive gently for a while. Listen for any exhaust leaks under the hood and under the car when the engine is idling, and tighten or realign where necessary.

Note any rattles or banging against the underside of the car that indicate some adjustments to the pipes or mountings may be necessary. Check periodically that all the connections remain tight and secure. Enjoy your added power and sweet new sound!

Now that you’ve learned all about exhaust systems, be sure to read:

Thanks for reading.

-Sean from ShortRam.com

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