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Top 5 Aftermarket Exhaust Kits

Magnaflow Cat-Back 19100 Exhaust Kit for the Ford Mustang
iKnowAuto Staff
Whether you need just a tad more power, want to save a bit of weight, have more style, or just want an extraordinarily sounding machine, aftermarket exhaust systems are the way to go. In that regard, here is our list of the top five aftermarket exhaust kits which just may help you rig out your car with a proper exhaust. However, before you decide what may work for you, you should read a detailed explanation of how aftermarket exhausts work and how much power do they really provide. If you, however, want to see the products, just scroll down.
MAR 14, 2019

How much power can you really get after upgrading your exhaust?

The answer to this question could be “none.” Zero power, nil, naught, nothing at all. The bang in the cylinder will be the same as before. Yet, an aftermarket exhaust kit could make your wheels spin quicker. In the simplest of terms, by installing an aftermarket exhaust kit, the engine power can be harvested more effectively and efficiently. Thus, a test of the engine power on the dyno with an upgraded exhaust could result in higher torque and HP values. Various aftermarket exhaust kit producers promise 5-10 percent gain (some promise 5-10hp), but that really depends on a number of factors. Also, the bigger and the more powerful the engine, the better the results. However, do not expect to gain 50hp on a 500hp V8 by installing a less restrictive exhaust.

How is it possible to gain power at all?

Technically, less restrictive aftermarket exhausts enable the moving piston in its exhaust cycle (fourth cycle in a four-stroke engine) to lose less energy when pushing out exhaust fumes. All the energy saved in that fashion will be used elsewhere - like spinning up the crank and eventually getting to the wheels. See, factory installed exhausts are engineered according to strict corporate ideology, market niches the car is sold at and government regulations.

On modern cars, exhaust systems have to compile with requirements like these:

  • Be economically sound (basically, not be too expensive to produce)
  • Have exceptional engine sound deadening properties (so it complies with sound regulations all over the world)
  • Affect engine in such a way to provide optimal power and torque properties required by the car manufacturer, and most importantly
  • Reduce emissions of harmful particles like NOx, CO, and unburnt hydrocarbons

To do all of this, exhaust pipes feature a number of devices attached to them:

  • O2 sensors before and after catalytic converters
  • Catalytic converters (usually more than one that reduce harmful particle emissions by converting them into less harmful molecules and particles)
  • Resonator before muffler (to cancel out some of the sounds) - this one is usually found on higher end cars
  • Restrictive muffler (also to cancel as much sound as possible)
  • With modern diesel engines, exhaust systems have special AdBlue injection ports added to them (to further reduce emissions)

Engineering such an intricate system makes an exhaust rather complicated - with a number of bends and curvatures in front of which (at higher RPMs) exhaust gases create points of high pressure. That pressure has to be counteracted by piston movement (engine power - HP). The only way aftermarket exhaust systems can improve the exhaust flow is to remove as many restrictions between the cylinder exhaust to the tailpipe as possible. To achieve that, producers of aftermarket exhaust systems tend to install new headers, high-flow catalytic converters, remove as many curvatures from the pipes as possible and install high-flow mufflers. Sure, this changes the nature of the exhaust system releasing a bit more emissions and a lot more of engine sound. However, it does ease the job of pushing out exhaust fumes from the cylinders. All that saved momentum eventually ends up powering the vehicle rather than pushing out exhaust fumes.

Finally, how much will I gain?

Obviously, the answer to the question posed above cannot be clear. It all comes down to the quality of the aftermarket exhaust kits, how different is it physically compared with the stock one, the diameter of the exhaust pipes and the number of removed restrictors (whether they are catalytic converters, resonators or just plain curves and bends on the pipes). Usually, the larger diameter of exhaust pipes equals the better flow of the exhaust at higher RPMs. However, that also means that at lower RPMs the engine has to work more to push out the exhaust fumes. Because of that, you would probably see lower torque numbers at lower RPMs on the dyno. It also means higher torque and power at higher RPMs.

Do not, however, expect any miracles in terms of wheel horsepower gain. 3-5 percent is your best bet. Anything above? Awesome. Whether your Team Gibson or Team Magnaflow, there is a wide range of performance exhaust systems. Now, after you mastered the basic science behind exhausts and their function, let’s jump into the what are the best exhaust systems.

Magnaflow Street Cat-Back Exhaust (#19100)

Magnaflow Cat-Back 19100 Exhaust Kit for the Ford Mustang

We are starting with the Magnaflow Cat-Back 19100 Exhaust for the latest generation of the Ford Mustang GT. With so many Mustangs on the streets, Magnaflow, one of the most famous exhaust producers, unveiled a cat-back five-part exhaust specially designed to provide a bit more power, lower the weight and improve the sound of the famed five-liter V8 Coyote under the bonnet.

This Ford Mustang GT exhaust kit contains X-Pipe (mounted after catalysts), mid pipes (as straight as possible) and mufflers with dedicated tailpipes.

As the whole exhaust is made out of stainless steel with polished tailpipes and high-quality finish, Magnaflow is certain of its longevity. Warranty? Lifetime!

Gibson Cat-Back Exhaust System Stainless Steel Dual Split Exit(#69545)

Gibson Performance Exhaust Cat-Back Dual Split Exhaust System for Ford F-150 5.0

Gibson Exhaust Systems for the Ford F-150 5.0 can be described in two words - throaty and thrilling. It is loud and it will give you chills. As with every other Gibson Exhaust kit, this one for the truck “is designed to reduce back pressure with mandrel bent tubing and include a polished, intercooled T304 stainless steel tip(s).”

In essence, the Superflow Muffler with (CFT) Convergent Flow Technology will wake your neighbors up. How? This is how - just listen to it. That is what the Dual Split Cat back can do.

Thankfully, the Ford F-150 exhaust kit comes with amenities everyone will cherish:

  • Hassle Free Bolt-On Installation,
  • Enhanced Low and Mid-Range Power,
  • Powerful Exhaust Tones,
  • Minimal Interior Sound Levels,
  • Maximum Horsepower & Torque Gain.

Interestingly enough, Gibson promises horsepower gain of 15-20hp.

What I can say for sure is that it sounds startlingly aggressive, it is backed by a Lifetime Limited Warranty.

MBRP Automotive Jeep Performance Exhaust for the 2012-2018 (#S5526BLK)

MBRP Automotive Jeep Performance Exhaust for the 2012-2018 Jeep Wrangler/Rubicon 3.6L

As much as exhausts for streetcars can be sharpened to offer the best in terms of style, sound and city driving characteristics, the aftermarket exhaust kit for off-road vehicles can be adapted for use outside the roads. Sure, they cannot possibly differ dramatically compared with the standard aftermarket exhausts, but MBRP automotive showcases perfectly how they can. MBRP Automotive cat back exhaust crafted for the 2012-2018 Jeep Wrangler/Rubicon 3.6L comes with a single rear exit and is coated with a black finish. This provides exceptional protection against any off-road hazards which secures the longevity of the piece.

One of the most important characteristics of this Jeep aftermarket exhaust kit is the fact that MBRP kept mandrel bent tubing to minimal bend degree angles. As you may have learned above, this means that the engine needs less power to push out fumes from the combustion chamber. Less power used there means more power at the wheels.

MBRP promises that Jeep performance exhaust will use less gas, last longer and perform better.

There is no reason not to trust them as these exhausts were tested all across Rausch Creek, PA to the rock of Moab, UT and the Arctic of Northern Canada.

Mazda 3 2014-2018 Axle-Back Exhaust S-Type (#11918)

Borla S-Type axle-back exhaust for the 2014-2018 Mazda 3

Sure, cat back exhaust I have covered so far is the best bet when it comes to efficiency and power improvements, however, if you are on a tighter budget, but still want something cool, the answer is an axle back exhaust. Presented here by a Borla S-Type exhaust for the 2014-2018 Mazda 3, the axle back aftermarket exhaust comes with three different pieces - middle pipes and two mufflers.

In this case, the axle back exhaust can fit on all Mazda 3 hatchback cars with two-liter and 2.5-liter engine and a manual transmission. With a weight of only 18.9 lbs., it will even save you a few lbs.

Hedman Hedders X-Junction Crossover System 

Hedman Hedders X-Junction Crossover System

While axle-back systems would definitely help a bunch in terms of engine sounds improvement, what comes in front of it may be the most important factor for power gain. In that regard, here is an X-Junction Crossover System; 3" System - Universal Fit. Engineered in aluminized steel by Hedman Hedders, the system “will use 2 to 4 feet of the exhaust system from the headers on the back”. One can expect better exhaust flow due to less restrictive piping. X-Pipe will balance exhaust pulses from both sides for an exceptionally smooth exhaust.

Obviously, instructions do note that installation isn’t exactly hassle-free - some welding will be required. This is not a huge deal considering it has such an affordable price.