Collection: Performance Upgrades | Mercedes E550 CLK550 CLS550 5.5L V8

The M273 5.5L naturally aspirated V8 doesn’t get the recognition it deserves. Built on a solid foundation of German engineering, it delivers smooth, confident torque across the rev range with the desire to pull hard all the way to redline. But the stock engine is restrained by conservative factory tuning and a restrictive exhaust system. That’s where our upgrades come in.

Platform-Focused Performance

What sets the M273 apart from older platforms like the M113 isn’t just refinement — it’s the untapped power available up top. From the factory, it’s choked by an overly restrictive exhaust system. Freeing up that flow transforms the engine’s character, unlocking a crisp, responsive powerband that pulls hard through the mid and high RPM range — right where this platform wants to run.

These upgrades are tested and proven on models like the E550, CLS550, CLK550, S550, and SL550 with the M273 5.5L V8.

• ✅ Mid-length headers: Designed specifically for the 5.5L NA V8 architecture, our headers improve exhaust scavenging and flow without ground clearance issues or triggering CELs.
  🔧 View Headers for M273
• ✅ Custom ECU Tune: Calibrated to take advantage of the increased flow, sharper ignition timing, and improved fueling — our tuning solution is dialed to bring out the M273’s high-RPM potential in real-world driving.
  ⚙️ View ECU Tune for M273

Supporting Mods That Make a Difference

We recommend pairing your core upgrades with a few simple supporting changes that dramatically increase effectiveness:

• High-flow drop-in filters: Maximize intake airflow and throttle response.
• Proper exhaust configuration: Reduces backpressure, smooths exhaust pulses, and delivers a clean, refined tone at wide-open throttle.