Mercedes-AMG A45 & CLA45 Downpipe Guide — M133 M139 Catless vs 200-Cell, Power Gains & Sound (2026)
Why Upgrade the Downpipe on an AMG A45 / CLA45?
The Mercedes-AMG A45 and CLA45 use either the M133 (W176/C117, 2013–2019) or M139 (W177/C118, 2019+) turbocharged four-cylinder engine — the most powerful production four-cylinders ever built. The factory downpipe includes a restrictive catalytic converter close-coupled to the turbo. Upgrading to a high-flow downpipe is the most effective bolt-on for reducing turbo lag, increasing peak power, and adding exhaust character to these compact AMG models.
Catless vs 200-Cell — Comparison Table
| Type | HP Gain (with Stage 2) | Torque Gain | Emissions | Sound | Best For |
|---|---|---|---|---|---|
| Catless (race) | +50–80 WHP | +50–70 lb-ft | Off-road / track only | Aggressive, raspy turbo-four | Track builds, max power |
| 200-cell sport cat | +40–65 WHP | +40–55 lb-ft | Passes most tests | Sporty, refined | Daily-driven A45s/CLA45s |
Power Gains — Stage 2 with Downpipe
The M133 and M139 respond aggressively to reduced exhaust restriction. A catless downpipe alone adds 10–20 WHP, but the real unlock is the Stage 2 combination — downpipe plus ECU calibration. Stage 2 M133 builds typically reach 430–460+ WHP. The newer M139 (421 HP stock) can reach 480–500+ WHP with the same approach.
M133 vs M139 — Which Downpipe Do I Need?
- M133 (2013–2019 A45/CLA45/GLA45) — single turbo, transverse-mounted, specific downpipe design
- M139 (2019+ A45 S/CLA45 S) — redesigned turbo orientation and exhaust routing, requires M139-specific downpipe
Always confirm your engine code before ordering.
Installation
Single downpipe — one turbo, one pipe. Bolts to the turbo outlet with a V-band or flange and connects to the midpipe/catalytic section. 304 stainless steel with pre-welded O2 sensor bung. Installation takes 1.5–3 hours on a lift.