GR86 Subwoofer: How to Add One to Your Factory Stereo
If you are shopping for a GR86 subwoofer, the hard part is not the subwoofer. It is finding a signal to feed it. The factory head unit in the Toyota GR86 and Subaru BRZ has no RCA outputs, no subwoofer channel, and no remote turn on wire, which is why most people assume they have to rip the dash apart and start over.
You do not. The Beat-Sonic ENA-3S1 plug and play amplifier installs behind your factory radio in under an hour, gives your existing speakers real power, and includes a dedicated subwoofer RCA output plus a remote turn on wire. Install the amp now, add the sub whenever you are ready, and never cut a factory wire.
Why a GR86 Subwoofer Needs More Than the Factory Stereo
A powered subwoofer needs two things from the car before it will do anything useful. It needs a low level audio signal, normally delivered over RCA cables, and it needs a 12 volt remote wire that tells it when to wake up and when to shut off.
The factory system in the GR86 and BRZ gives you neither. Everything behind that screen is speaker level, and there is no spare turn on lead sitting there waiting for you. The usual workarounds are all compromises. Line output converters tap into speaker wires and add another stage of noise. Splicing into the harness leaves permanent damage and kills your resale. Replacing the head unit costs you the factory screen, the backup camera, and the steering wheel controls.
What you actually want is an amplifier adapter for factory stereo systems, one that solves the signal problem and the power problem at the same time. If you are still weighing whether an amp is the right first move, our breakdown of what a car amplifier actually does for factory speakers is a good place to start. You can also browse the full plug and play amplifier lineup to see what fits your car.
How the ENA-3S1 Creates a Subwoofer Output That Was Never There
The ENA-3 series was built around this exact problem. Instead of only boosting your factory speakers, it acts as the signal source your aftermarket gear has been missing.
Dedicated Subwoofer RCA Output
On the back of the amplifier you get a set of RCA outputs reserved for a subwoofer. That is a clean low level signal taken from the amp itself, not scraped off a speaker wire with a converter. Plug your powered sub straight into it.
Remote Turn On Wire
The kit includes a remote wire that carries the 12 volt trigger your subwoofer amplifier needs. It ships long enough to route back through the car, so you are not hunting for an ignition source under the dash or tapping a fuse.
Independent Front and Rear Gain Dials
The ENA-3S1 has separate gain adjustment knobs for the front and rear channels, so you can balance the cabin instead of turning everything up at once. One warning straight from the install: those dials have a hard stop at each end. Do not force them past it. We have had customers twist past the maximum point and destroy the amp doing it.
Auto Sense Turn On
The amp can wake up from either a speaker signal or an ACC signal. Some vehicles only offer one of the two. The GR86 and BRZ have both available, so either setting works and you can pick whichever is easier for your wiring.
The Install: Amp First, Subwoofer Later
The whole point of this approach is that you do the dash work once. Here is how the install goes in a GR86, start to finish in about an hour.
Open Up the Dash
Use a plastic panel removal tool so you do not scar the trim. Pop the side panel next to the radio, then the center piece, both of which are held by clips. Behind them is a Phillips screw. Remove it and the panel above lifts out on clips. Move to the driver side, pull the panel above the start button, then remove the vent above the screen. There is a connector behind that vent, so unplug it and set the vent aside.
Drop the Radio
Four 10 millimeter bolts hold the radio in, two on each side. Before you pull the unit out, lay a thick moving blanket or folded towel across the console. Rest the radio face down on it. That gives you clean access to every connector on the back without scratching anything.
Connect the Plug and Play Harness
Down at the bottom on the passenger side you will find a 10 pin and a 6 pin connector. Press the release tabs and work them free, then route the cables up where you can reach them. The Beat-Sonic harness in the kit has matching 10 pin and 6 pin ends. Car side plugs into the harness, harness plugs back into the radio, and the third leg runs to the amplifier. Nothing gets cut, and the whole thing comes back out without a trace if you ever sell the car.
Mount the Amplifier
The amp tucks into the cavity behind the radio with the included double sided tape. It is a snug fit. If you want more working room, back out the three Phillips screws holding the lower bracket, drop it slightly, and slide the amp in. Then reverse everything you took apart.
Connecting the Subwoofer When You Are Ready
This is where the upgrade path pays off. Whether you add the sub the same afternoon or two years later, the wiring is already sitting behind your dash.
Connect your powered subwoofer to the RCA outputs on the amplifier, then extend the remote wire toward the rear. If the sub lives under a seat, run the wire down through the center console. If it lives in the trunk, follow the door sills back and pick it up there. Zip tie the remote lead and label it if you are not using it yet, the way we do on customer cars, and it will be waiting for you.
For a look at the same idea on a different platform, see how we added a subwoofer to a 2024 Toyota Tacoma using the ENA-3T3.
Fitment and Choosing Your Kit
The ENA-3S1 covers the 2022 to 2026 Toyota GR86 and the 2013 to 2026 Subaru BRZ, along with other Subaru applications. The wider Encore Alpha family also covers Toyota, Honda, Nissan, Lexus, and Subaru vehicles, so the same subwoofer ready design is available well beyond the 86 platform.
Not sure which model number applies to your car? Our guide on picking the right Encore amplifier walks through the differences, and the ENA-3S1 install on a Subaru WRX shows the kit in another chassis. One important difference there: a WRX without Harman Kardon audio also requires the VAZ-A02K add-on module, so check which system your car has before ordering. If you are building the car out further, the throttle response controllers and everything else in the new products collection are worth a look.
Common Questions About Adding a Subwoofer to a Factory Stereo
Do I need the amplifier, or can I just add a subwoofer?
You need a signal source. The factory GR86 and BRZ head unit has no RCA output and no remote turn on wire, so a powered subwoofer has nothing to connect to. The ENA-3S1 supplies both.
Can I install the amp now and add the subwoofer later?
Yes. That is the reason the RCA output and remote wire are there. Do the dash work once, then connect a sub whenever you decide to.
Does this require cutting any factory wiring?
No. The kit uses a plug and play harness that sits between the car connectors and the factory radio. It is fully reversible and leaves no trace.
How long does the install take?
About an hour in a GR86 or BRZ, including panel removal and reassembly.
What do the front and rear gain dials do?
They set output level for the front and rear channels independently so you can balance the cabin. Never turn them past the physical stop, because that damages the amplifier.
Will I keep my factory screen and backup camera?
Yes. The factory head unit stays in the dash and keeps every function it had before.
Questions About Your 86 Platform Build?
We are a small team in La Mirada, California, and we answer our own phones. Orders placed on business days ship the same day, so the kit is usually moving before you finish reading the instructions. If you are unsure which variant matches your model year or how to plan the subwoofer side of the build, reach out to the Beat-Sonic support team and we will walk you through it. You can also browse everything we make or dig into the stereo integration lineup.