Exhaust valve talk comes with a lot of jargon, and half of it means the same thing. Here's every term you'll run into, explained in plain English, with links to the guides that go deeper.
Key takeaways
- Valved exhaust, active exhaust, sports exhaust and exhaust flaps usually describe the same hardware: a flap the car opens and closes.
- The valve actuator moves the flap, and the ECU tells it when.
- An exhaust valve controller lets you hold the valves open on demand and hand control back to the car.
- A blanking or bypass plug locks the valves open; a bare unplug usually throws a check engine light.
- Controllers work on petrol cars with electric actuators, not vacuum systems or diesels.
01A to C
Active exhaust. An exhaust with controlled valves that the car opens and closes based on drive mode, revs, load and throttle. Another name for a valved exhaust; see what is a valved exhaust.
Actuator. The small motor connected to the exhaust valve that turns the flap. On modern cars it's electric and takes its orders from the ECU.
Aftermarket exhaust. Any exhaust that replaces the factory one, from a cat-back to a full system. If it keeps controllable valves run by the factory actuators, a controller can still work with it. The help centre covers controllers with aftermarket exhausts.
Blanking plug. A small plug fitted in place of the valve actuator's connector. It stops the check engine light a bare unplug usually causes, but leaves the valve locked open with no quiet mode. Also called a bypass plug.
Bypass plug. See blanking plug.
Catalytic converter. The emissions device near the front of the exhaust.
Cat-back. An aftermarket exhaust that replaces everything from the catalytic converter back. It changes tone and volume, and often costs $1,000 to $3,000+ fitted. Compared in controller vs catback vs bypass plug vs tune.
Check engine light. A dashboard warning that the ECU has stored a fault. Unplugging a valve actuator usually triggers one; a blanking plug avoids it, and a quality controller throws no check engine light.
Coding. Changing the car's software so the valves open more often or in different drive modes through the use of an OBD tool. See do you need a tune to open your exhaust valves.
Cold start. The first start of the day. On many cars the valves open briefly at start up, which gives you a preview of the open valve sound while stationary.
Control box. The module most wired controllers mount somewhere under the car, or in the boot / trunk with cables running to each valve. A wireless controller like 11MODE has no control box.
02D to K
Diesel exhaust valve. A valve on a diesel engine that exists for emissions, not sound. Controllers don't work on diesels.
Drive mode. Settings like Comfort, Sport, Sport Plus, Race, Dynamic, M that change how the car behaves. They can change when the valves open, but it varies from car to car, and you can't rely on any mode to keep them open all the time.
Drone. A low, constant hum through the cabin at a steady cruise. Open valves can bring drone on some cars, which is why reverting to factory matters.
ECU. The engine control unit, the car's computer. It decides when the valves open and sends the command to the valve actuators.
Electric actuator. The dominant actuator type on modern cars: an electric motor that moves the valve on the ECU's command. Controllers like 11MODE work with electric actuators only.
Exhaust flap. Another name for an exhaust valve.
Exhaust valve. A flap inside the exhaust, usually near the muffler, moved by an electric valve actuator. Closed, it sends gas through the quieter path. Open, it gives the gas a more direct route out. How they work is in how OEM exhaust valves work, and the help centre shows where the exhaust valves are located.
A plug and play device that intercepts the signal to your factory electric exhaust valves and lets you override it, so you can hold the valves open on demand and then hand control back to normal factory behaviour. It allows for maximum exhaust flow for the most sound from the exhaust.
Factory control. The car deciding for itself when the valves open. With 11MODE, pressing OFF returns full factory control.
Fault code. A code the ECU stores when it detects a problem, often alongside a check engine light. An OBD-II scan tool can read and clear it.
Fitment. Whether a product suits your exact make, model and year. 11MODE fits 1,000+ make, model and year combinations across 25+ brands; check yours in the fitment finder.
GPF or OPF. A gasoline (or Otto) particulate filter, an emissions device fitted to many newer petrol engines. It also softens exhaust sound. Explained in why modern performance cars sound so muted.
HomeLink. The garage door buttons built into some cars. The 11MODE remote can be paired to HomeLink or similar buttons for convenience, with separate buttons for ON and OFF. See pairing with HomeLink.
03L to R
Limp mode. A protective mode some cars enter when the ECU detects a fault, limiting performance until it's fixed. A bare unplug of the valve actuator can trigger it.
Loud setting. The car's loudest drive mode, although the valves are still not always fully open.
Memory function. A feature on current 11MODE controllers that remembers your last setting, ON or OFF, the next time you start the car. Details in the memory function article.
Muffler. The silencing box near the back of the exhaust. Most sound valves sit near it.
Muffler delete. Cutting out the muffler and replacing it with a straight section. Loud all the time and effectively permanent.
OFF. The 11MODE button that hands full control back to the car. It never forces the valves closed, because a car may need them open under high load. Explained in why OFF doesn't close the valves.
ON. The 11MODE button that keeps the valves fully open in any drive mode.
Plug and play. Fits using the car's existing connectors, with no cutting, splicing or software changes.
Professional installation. As with all car mods, professional installation is always recommended.
Remote. The fob that controls a controller. The 11MODE remote works straight out of the box with no need to pair, and one remote runs both valves on twin valve cars.
Resonator. A chamber in the exhaust tuned to cancel certain frequencies, often to reduce drone.
Reversible. A mod you can fully undo, with no cutting, welding or software change, leaving the car as it left the factory.
04S to Z
Sport mode. A drive mode that opens the exhaust valves, but not all the way and all the time.
Straight pipe. An exhaust with no mufflers or silencers. Loud all the time, with no way back to quiet, and not road legal in many places.
Tune. Software changes to the ECU. A performance tune changes how the engine makes power; valve coding changes when the valves open.
Twin valve. An exhaust with two valves, usually one per side. The 11MODE kit for a twin valve car comes with two controllers; see 1 or 2 controllers.
Vacuum actuator. An older valve design, common before the mid 2010s, moved by vacuum through a solenoid and diaphragm. Controllers like 11MODE don't work with vacuum systems.
Valved exhaust. An exhaust with one or more valves the car can open and close. The umbrella term for active exhaust, sports exhaust and exhaust flaps.
Valvetronic. A word drivers often use loosely for a valved exhaust. It's also the name of a BMW engine technology that has nothing to do with exhaust valves, and part of the name of an aftermarket exhaust brand.
Variable muffler. A muffler with a valve built in. Can be found as an aftermarket product for cars that never had valves.
Wireless controller. A controller with no wiring harness, control box or cables to route. 11MODE plugs in at the valve actuator in minutes with no tools.
Noise regulations vary by country and state, and these products are sold for off-road and track use, so check the rules where you drive before running your valves open on the street.
05Frequently asked questions
What's the difference between an exhaust valve and an exhaust flap?
Nothing. They're two names for the same part: a flap inside the exhaust that the car opens and closes.
What does an exhaust valve actuator do?
It turns the valve. The actuator is a small motor connected to the valve that takes its orders from the ECU.
Is a blanking plug the same as a controller?
No. A blanking plug locks the valves open with no quiet mode. A controller holds them open on demand and hands control back to the car when you press OFF.
What does valvetronic mean on a car?
It usually means a valved exhaust. Strictly, it's also a BMW engine technology unrelated to exhaust valves.
Do I need a tune to open my exhaust valves?
No. A plug and play controller opens them without changing any software. More in do you need a tune to open your exhaust valves.
06The bottom line
Once the jargon's out of the way, the idea is simple: your car may already have a loud setting, and the car decides when and how much you hear. If your car has factory electric exhaust valves, check your car and turn it to 11.
