Valved exhaust: how it works, cost, retrofit and inspection

The short answer. A valved exhaust, also called a valve exhaust or active exhaust, is an exhaust system with motorised valves built in. With the valves closed, the gases pass through the silencers: the car keeps a sound close to stock. With the valves open, they take a more direct route: the engine is heard in full. You control them through the car's factory drive modes, if it has them, or with the Rog remote.

Here is how a valved exhaust works, what shapes its sound, what it costs, how to retrofit one to your car and what to know for the MOT or vehicle inspection.

What is a valved exhaust.

A conventional exhaust has a single path: the gases always pass through the same silencers, and the sound is fixed. A valved exhaust has two. One or more valves, small pivoting plates in the rear silencer or just before it, choose the path of the gases on demand.

Valved exhaust, valve exhaust, active exhaust: the name changes with the brand and the forum, the part is the same. The term "Valvetronic" is also used for these systems, yet at BMW, Valvetronic means variable intake valve lift inside the engine, with no link to the exhaust. And the valves of a valved exhaust are not the engine's valves: those sit in the cylinder head, these sit in the exhaust system.

How a valved exhaust works.

The valve is moved by a small electric motor, or by vacuum on some factory systems. It pivots to open or close a passage. The gas path changes instantly, and the sound changes with it.

Closed or open: what changes.

With the valves closed, the gases pass through the rear silencer and the cabin stays quiet at cruising speed: our systems are designed to avoid booming, known as drone (does a valved exhaust drone?). With the valves open, the exhaust breathes freely, on the road and on track.

What makes the sound of a valved exhaust.

The valves decide when the sound comes out. The sound itself depends on the exhaust, and at Rog you choose it when you order:

• The design. Standard on every system; on several BMW M models, Equal Length, pipes of identical length for a purer sound, and Equal Length + Z-pipe, our best system (Equal Length and Z-pipe).
• The material. 304 stainless steel, with a warm, round sound, or titanium, lighter, with a crisper sound, in a brushed, gold or purple finish (stainless steel or titanium: which to choose).
• The character. On many models, at the same price: straight pipe for the raw sound of your engine, or resonator for a rounder, slightly softer voice that is just as sporty (straight pipe or resonator).
• The intensity. You tell us the intensity you want on a scale of 1 to 10, and the system is prepared accordingly.
• The front section. Depending on the model, the factory front section is kept, or replaced by a version with a 200 or 100 cell sports catalytic converter; on a turbocharged engine, this is the downpipe (downpipe: what is it?, 200 cell sports catalytic converter).

Factory control or Rog remote.

Two control options, chosen when you order:

With the Rog remote, the valves stay as you set them: open, they stay open; closed, they stay closed, whatever the drive mode.

1/2Remote

2/2Control box

Retrofitting a valved exhaust to your car.

It is possible on almost every car, with or without factory valves. The factory exhaust is not drilled to graft in a valve: it is replaced by a system designed for your model, with the valves built in.

• Your car already has valves (many BMW M, Mercedes-AMG, Audi RS, Golf R, Porsche): you keep the factory control with your valves, or switch to the Rog remote.
• Your car has none: the exhaust arrives with the Rog valve system and its remote.

The Rog exhaust fits in place of the factory system, on the original mounting points, without touching the engine or the ECU. Each system is built to your VIN and checked before production: it fits your car perfectly.

How much does a valved exhaust cost.

At Rog, a complete valved exhaust, from the catalytic converter to the tailpipes, is configured on your model's product page. Examples (the price is shown in your currency on each product page):

Volkswagen Golf 8 R, BMW M340i G20 / G21, Audi RS3 8Y, Mercedes-AMG A45 / A45 S W177, BMW M2 G87, BMW M3 / M4 G80 / G81 / G82 / G83.

What changes the price: the material (stainless steel or titanium), the design, the front section, the valve control and the tips. Free delivery, manufacture and delivery in 20 working days, 3-year warranty. To compare with the big brands, see the price of a performance exhaust and our brand comparison.

Valved exhaust and the MOT.

For the MOT or your vehicle inspection, present the car with the valves closed: the sound is then close to stock. Emissions control stays as it left the factory if you keep the factory front section; with a 200 cell sports catalytic converter, it is retained. A decat version is for track use only. The details, point by point: passing the MOT with a modified exhaust.

A system calibrated to keep the noise level of the original type approval sounds almost like the factory exhaust. The valves give you both: restrained every day, unleashed when you decide.

The rules in your country: United Kingdom (MOT) · Ireland (NCT) · United States · Canada · Australia.

Which cars.

Rog builds valved exhausts for more than 400 models from 28 brands. The most requested generations:

• BMW M3 / M4 G80 / G81 / G82 / G83
• BMW M2 G87
• BMW 3 Series G20 / G21
• BMW 1 Series F20 / F21
• Volkswagen Golf 8 GTI / R
• Volkswagen Golf 7 GTI / R
• Audi A3 / S3 / RS3 8Y
• Audi A3 / S3 / RS3 8V
• Audi A4 / A5 / S4 / S5 / RS4 / RS5 B9 / F5
• Mercedes A-Class W177
• Mercedes CLA C118 / X118
• Mercedes C-Class W205
• Porsche Macan 95B

All brands and all models: valved exhausts by brand.

What the people who have tried them say

"I'm rediscovering my car. Discreet during the week, wild on Sundays. Thanks, Rog."

"Fitting was simple and the sound is perfect. And I can get home late without bothering anyone."

"I was worried it would be a gimmick. Turns out I can't do without it."

Frequently asked questions.

Does a valved exhaust add power?
The system on its own mainly brings sound and a little less weight. On a turbocharged engine, the measurable gain comes from the front section, the downpipe, together with an ECU remap.

Do you need a remap to fit a valved exhaust?
No. The system fits without touching the engine or the ECU. If you also replace the front section, a remap is recommended to unlock the power and keep the engine free of warning lights.

Can you drive with the valves open all the time?
Technically, yes: with the Rog remote, the valves stay in the state you choose. For daily driving and the MOT, keep them closed; open them when the road and the moment allow, and on track.

Does a valved exhaust drone on the motorway?
No. With the valves closed, the gases pass through the rear silencer and the cabin stays quiet at cruising speed: our systems are designed to avoid drone.

Can I keep my factory valves?
Yes, on models that have them: choose "Valve system: Factory" when you order, the exhaust arrives with their mounts and you control them as before.

Valved exhaust, valve exhaust, active exhaust: what is the difference?
None, they all describe the same system with the same part. The engine's own valves, on the other hand, are inside the engine.

How long does it take to receive a Rog valved exhaust?
20 working days from order confirmation to delivery, including manufacture to your VIN. Free delivery, 3-year warranty.