Mercedes-AMG A45 W176 Valved Exhaust System (2014-2018)

The Mercedes-AMG A45 W176 exhaust in detail.

When the A45 W176 arrived, no production two-litre engine produced as much power. Its M133, the first turbocharged four-cylinder developed entirely by AMG, drew 360 hp and 450 Nm from 1,991 cc, then 381 hp depending on the phase, over the 2014 to 2018 model years covered by this page. Forged parts, twin-scroll turbo, hand assembly: racing mechanicals, with the soundtrack of a sensible compact.

Oversized silencers erase almost all of the engine’s character. The Rog valved cat-back, or valve exhaust depending on the term you search for, replaces pipes, silencers and tips: open, a snarling tone, an aggressive climb and crackles on the overrun; closed, the W176 regains the discretion it has always been capable of. The A45 W177 that followed has its own page, as do the CLA45 C117 and GLA45 X156, its M133-engined cousins.

Your VIN, taken from field E of the registration document, is used to manufacture the exhaust. Fitting takes about two hours on a lift; clamps and gaskets are enough, the welding kit stays in the cupboard. If the car has kept factory valves, their control is retained; otherwise, a box housed in the boot and a two-button remote take over.

After the silencer, the second restriction on the M133 is the downpipe that leaves the turbo and carries the catalytic converter; on this page it is listed under the “Manifold” option. In 200-cell form, emissions control stays in place. The freer-flowing options, the 100-cell version, which inspection may or may not accept depending on the vehicle and your country’s rules, and the decat version, reserved for track use, are aimed at a different kind of A45. Without an ECU remap, this part adds no horsepower, just sound and a few kilos less. That leaves the choice of material for the cat-back: 304 stainless steel for year-round driving, or titanium to save around 40% in weight, supplied in brushed, gold or purple.