Changing Your Tacoma’s Voice with Mufflers

A muffler is simply a device that is designed to reduce the noise emitted by the motor while maintaining engine power. When viewed from the outside, the muffler in your Tacoma may look like a basic metal case. If you were cut it open to get a cross-section view, the innards of a muffler contain a series of interior pipes, passages, and chambers.

The goal is to route the high-velocity exhaust gasses through the series of resonating chambers inside the muffler. This will serve to harmonically tune or cancel out the noise created by the hot exhaust gasses. This is the reason why the factory mufflers are quieter compared to aftermarket units. 

But there’s a catch. The process of filtering out the exhaust sound may ​rob the motor of horsepower, as the engine does have to exert effort to push the exhaust through the various chambers in the muffler. ​

Whether you have a four-cylinder or V6 Tacoma, the muffler is connected directly to the tailpipe, which is located on the rear passenger side of the truck. 

In the 2005 to 2017 Toyota Tacoma with a 110-inch and 128-inch wheelbase, the factory Y-pipe has a ​diameter of 2.25-inches. The stock exhaust piping has a diameter of 2.398-inches or 2 1/4”. Most aftermarket axle-back or cat-back exhaust kits will have larger 3.0-inch or 3.5-inch pipes to improve the exhaust flow. ​

Compared to the restrictive stock mufflers, aftermarket units are designed to open up or free-up the flow of hot exhaust. This means a significant reduction in engine backpressure, which means the exhaust gasses can flow at a faster rate with less effort from the engine. The result is more horsepower and torque output leading to mildly better performance accompanied by a more aggressive exhaust sound.

Replacing the factory mufflers in your Toyota Tacoma is one of the basic mods you can do in your own garage. Most aftermarket performance mufflers can be installed easily using simple hand tools. Depending on the year model and muffler set-up in your Tacoma, only minor cutting is required. There is no need for welding, either!

When installed on an otherwise stock Tacoma, owners can expect a small boost in horsepower and torque - in the neighborhood of 3-5 horsepower - dependent on the exact design of the muffler and which engine it is installed on. Besides the obvious gains in horsepower and deeper exhaust sound, aftermarket mufflers are manufactured utilizing high-quality stainless steel or aluminized steel. Aluminized steel is the choice of OEM systems and many aftermarket manufacturers also produce their entry-level exhaust systems out of aluminized steel to keep costs down.

Stainless steel is the next step up, with manufacturers either using 409-grade or 304-grade stainless steel. The former, 409, has more or less been specifically developed with the automotive exhaust industry in mind. It has very good temperature characteristics so it should not discolor. However, it does have a lower chromium content, between 10.5-11.75% which does make it susceptible to eventual surface corrosion when exposed to cold weather climates (and corrosive agents such as road salt). 

304-grade stainless steel would be considered the premium choice for a muffler. With a chromium content nearly double - 18-20% - that of 409-grade steel, 304 is all but impervious to rust. T304-grade mufflers will, however, change to a golden brown color over time due to the heat cycles. And of course, a 304-grade aftermarket muffler is likely to be the most expensive.

There are generally three types of performance mufflers:

1. Reactive mufflers: This is the most basic type of muffler and is generally considered as restrictive mufflers. Reactive mufflers are excellent when it comes to noise reduction, but they generally fare poorly in terms of exhaust flow. The main goal in designing a reactive muffler is to minimize the number of restrictions by utilizing a set of internal tubes and sound chambers inside the muffler. Quality aftermarket reactive mufflers such as Corsa and Flowmaster utilize special chambers and delta plates to literally deform the sound waves created by the exhaust. The system will divide the exhaust flow and bring it back together to cancel out some of the noise frequencies.

2. Absorptive mufflers: If you are looking for a more aggressive exhaust sound, nothing comes close to an absorptive muffler. This type of muffler has been around since the 1950s and is popular with hot rodders and engine tuners. Absorptive mufflers have a straight-through design. The inside of the muffler has a perforated tube and contains a packing material that absorbs some of the unwanted sound (which causes that annoying droning sound in some units).

3. A combination of both reactive and absorptive: This type of muffler is considered by many to be the best in terms of reducing backpressure and producing a better sound. By combining the qualities of a reactive and absorptive muffler, the combination of two designs offers a better balance of sound and exhaust flow. 

Generally speaking, the exhaust sound is correlated to the amount of power produced by the motor. A louder exhaust note means more power is retained by the motor, which can be unleased after stepping on the gas pedal. 

When it comes to ease of installation, bolt-in or clamp-in mufflers are the preferred choice. Welding the mufflers will require the skills of a professional. If done right, welding the muffler will produce a stronger bond while preventing exhaust leaks. Do it wrong, however, and you will end up with an inefficient exhaust system. For the casual backyard mechanic, a bolt-in muffler is the easiest to install (specifically if it is an axle-back system with leak-proof ball-and-socket joints). A proper weld will also ensure a leak-free system and be structurally more sound.

The answer will depend on your budget and the amount of performance gains. Full exhaust kits (commonly referred to as cat-back exhausts) are more expensive compared to replacing the mufflers only (also called axle-back muffler kits). If you are tuning your Tacoma for moderate performance gains and a better exhaust sound, you can do no wrong with an axle-back exhaust kit.

However, if you are looking to squeeze out every ounce of horsepower from the four-cylinder or V6 motor in your Tacoma, full exhaust or cat-back exhaust kits are a better option. This also holds true if your Tacoma is equipped with go-fast engine mods such as modified cams, headers, or forced-induction.

When it comes to extreme off-road applications, your Tacoma will benefit greatly from a cat-back exhaust kit. However, you need to decide if the cost of the cat-back system is worth the potential power gains. Since a cat-back exhaust kit contains more parts (longer and larger piping, mufflers, etc.), it is more expensive than a set of axle-back mufflers. 

But if your Tacoma is primarily tuned for street applications, upgrading the stock mufflers to an aftermarket axle-back exhaust is a more economical way to achieve marginal gains in horsepower and sound.