BRZ, FR-S, and GR86 Exhaust Upgrades: What a Cat-Back Actually Changes

Exhaust is where most owners of this chassis start, and it is the modification they ask about before they have even taken delivery of the car. Atomic Autosports is a performance auto and motorsports shop in Wickliffe, Ohio, specializing in exhaust systems, suspension upgrades, and track preparation for enthusiast vehicles including the Subaru BRZ, Scion FR-S, and Toyota 86 and GR86. We install exhaust on this platform regularly, and the questions that come across the counter are consistent enough to answer in one place.

What follows is what a cat-back system actually changes on a naturally aspirated 86 chassis, how the choice differs between the older and newer cars, and how to think about the decision before spending the money.

What Does a Cat-Back Exhaust Actually Change on a BRZ, FR-S, or GR86?

A cat-back exhaust system replaces everything behind the catalytic converter. On this chassis that means the mid pipe, the muffler, and the tips come off as a group and go back on as a matched set. Nothing forward of the converter is touched, which is the reason a cat-back is the least complicated exhaust modification available for these cars and the one that raises the fewest questions about emissions compliance.

The practical result of replacing that section is reduced restriction in the exhaust path behind the converter and a change in the character of the exhaust note. On a naturally aspirated engine the note is the headline. The flat four in this chassis has a distinctive sound that the factory system deliberately mutes in the interest of cabin quiet, and opening up the cat-back section is what lets that note through.

What Is the Difference Between Axle-Back and Cat-Back on the 86 Platform?

An axle-back system replaces only the rearmost section, from the rear axle back through the muffler and tips. A cat-back replaces that same rear section plus the mid pipe ahead of it. Axle-back is the smaller job and the smaller change. Cat-back is the larger job and the larger change, because it addresses more of the restriction in the system.

For an owner whose goal is a modest change in tone without committing to the full system, axle-back is a legitimate stopping point. For an owner who intends to keep the car and add supporting modifications over time, the cat-back is generally the better value, because an axle-back bought first tends to get replaced later rather than kept.

Does an Exhaust Add Horsepower to a Naturally Aspirated BRZ or GR86?

This is the question that deserves the most honest answer, and the honest answer is that on a naturally aspirated engine a cat-back exhaust is primarily a sound and character modification rather than a power modification. Gains on a naturally aspirated four cylinder from the cat-back section alone are modest. Any shop or manufacturer quoting a dramatic figure from a cat-back on a stock 86 is quoting something other than what the part does in isolation.

We will not publish a horsepower figure for a system we have not measured on a specific car with a specific configuration, because the number depends on the rest of the setup and on the dyno it was measured on. What we will say is that owners who buy a cat-back for the sound are satisfied with the result, and owners who buy one expecting a transformation in acceleration are usually not. Setting that expectation correctly before the purchase is more useful than a number that will not hold up.

What Should You Expect from Exhaust Drone on a Street Driven 86?

Drone is the resonance an exhaust system produces at steady cruising speed, and it is the single most common regret on this platform. The 86 chassis is light and the cabin is small, which means the interior is less forgiving of a resonant system than a heavier car with more sound deadening would be.

Drone characteristics vary meaningfully between manufacturers and between systems from the same manufacturer, and the difference between a system that is pleasant on a two hour drive to Mid-Ohio and one that is exhausting on the same drive is not something you can read off a spec sheet. This is worth a conversation before the order goes in rather than after the box arrives. Tell us how the car is actually used, how much of its life is highway miles, and how loud you want it at cruise, and the recommendation follows from that.

Does the FA20 or FA24 Change Which Exhaust You Should Buy?

Yes, because they are different engines in different generations of the car and the parts are not interchangeable across them.

The first generation cars, sold as the Scion FR-S, Subaru BRZ, and Toyota 86 through the 2020 model year, run the 2.0 liter FA20. The second generation cars, the GR86 and the current BRZ, run the larger 2.4 liter FA24. Exhaust systems are built for one generation or the other, and fitment is generation specific. Confirm the model year and generation before ordering, because the most avoidable problem in this whole process is a system that will not bolt to the car it was bought for.

What Does a Correct Exhaust Installation Look Like on This Platform?

Exhaust packaging under this chassis is tight, and the difference between a clean installation and a rushed one shows up immediately. A system that is not seated properly will sit slightly off, contact the underbody over bumps, or leave the tips visibly uneven in the rear valance. Getting the hangers seated correctly and the tips sitting square is most of the work.

The other detail that separates a finished job from a returning one is the flange gasket. Reusing a compressed factory gasket is one of the more common causes of a small exhaust leak after an otherwise clean installation, and a leak at the flange affects both the sound of the system and the readings from the sensors around it. Replacing the gasket during the install is a small line item that prevents a return visit and a frustrating chase for a rasp that was not supposed to be there. Every exhaust installation we complete at Atomic Autosports includes a new flange gasket and a check of fluids and tire pressures before the car leaves.

Is Exhaust the Right First Modification for a BRZ, FR-S, or GR86?

For a lot of owners it is, and there is good reason for that. It changes the daily experience of the car immediately, it does not compromise reliability, and it does not commit the owner to supporting modifications the way forced induction does.

The case against going exhaust first is worth hearing too. If the car is headed for track days, the money is better spent first on the items that determine whether the car is safe and consistent at speed, which means tires, brake fluid, pads, and an alignment set for the way the car will actually be driven. An exhaust makes the car more enjoyable on the drive there. It does not make it faster once it arrives.

If the plan is to build the car over several seasons, this ordering question is worth a conversation rather than a guess. Apex Club members get an annual one on one consultation covering exactly this kind of sequencing, along with fifteen percent off parts and labor through the year and priority booking when the schedule tightens up in season. Details are at https://atomicautosports.com/product/apex-club/.

Where Can You Get a BRZ or GR86 Exhaust Installed Near Cleveland?

Atomic Autosports is at 29251 Anderson Road in Wickliffe, Ohio, serving Cleveland and the surrounding Northeast Ohio enthusiast community. We install exhaust systems on the BRZ, FR-S, and GR86 platform regularly, and we work on these cars for owners who drive them on the street, at autocross, and at track weekends at Mid-Ohio, Nelson Ledges, Grattan, GingerMan, and Watkins Glen.

We also talk through platform decisions like this one on the Late to Grid podcast, which covers motorsports, performance driving, and car culture from the shop’s own perspective. Episodes are at https://atomicautosports.com/late-to-grid/podcast/.

Frequently Asked Questions

Get a Straight Exhaust Recommendation

If you are choosing an exhaust for a BRZ, FR-S, or GR86 and want a straight answer about how a given system will sound at cruise and how it will fit your car, bring us the year and the way you drive it and we will give you a recommendation you can live with. Atomic Autosports, 29251 Anderson Road, Wickliffe, OH 44092. Call (216) 329-4005 or book at atomicautosports.com.