C300 / GLC300 / E300 M274 Turbo Upgrades | ECU Tuning & Performance

Mercedes C300 / GLC300 / E300 M274 Mods & Performance Upgrades

The M274 2.0L turbo (W205 C300, X253/X256 GLC300, W213 E300, R172 SLC300) pairs a small turbo with a 4-cylinder design—ideal for low-to-mid range boost and daily drivability. If you’re hunting proven Mercedes C300 performance parts or GLC300 tuning, start where it matters most: downpipes for faster spool, stronger mid-range, and the sound you want.

C300 with ECU tune + exhaust mods — hear the pops & bangs potential.

Featured: Catless Downpipes for M274

M274 Catless Downpipe — W205 C300 / GLC300 / E300 / SLC300
✅ Guaranteed Fitment
🚚 Ships in 1 Business Day
🧰 CEL Transparency
M274 Downpipe for Mercedes C300 / GLC300 / E300

M274 Catless Downpipe

  • Real gains: quicker spool, noticeable mid-range punch, more aggressive exhaust note.
  • Fitment focused: direct bolt-on for C300/GLC300/E300 (M274).
  • Built to run: TIG-welded stainless, proper flanges, hardware compatibility.
  • CEL transparency: installing downpipes may trigger a CEL; an M274 ECU tune is recommended to prevent this and unlock full performance.

Off-road use where permitted — see Fitment & Use Policy below.

Recommended Mod Package — Downpipe • M274 ECU Tune • Intake

  • M274 ECU tune: optimized maps, better throttle, prevents CEL after downpipes.
  • Catless downpipe: less restriction, faster spool, stronger mid-range.
  • High-flow intake/filters: simple airflow improvement; easy install and maintenance.

Result: ~300 HP / 330 lb-ft with everyday reliability.

M274 ECU Tune (C300 / GLC300 / E300)

Pairs perfectly with downpipes to prevent CEL and maximize gains. Smooth drivability with stronger mid-range.

View Tune

Braided Brake Lines — W205 / W213

Firmer pedal and repeatable stops to match your performance upgrades. Easy install, reliable upgrade.

Shop Lines

High-Flow Intake / Filters

Simple airflow bump for GLC300 and E300. Budget-friendly, quick install, easy maintenance.

Find Filters

Why Buy Here — Curated M274 Parts for C300, GLC300 & E300

  • Model-specific curation for M274 platforms (C300 / GLC300 / E300).
  • Real ownership experience: we’ve run C300 and GLC300—know what actually works.
  • Fast handling: ships within 1 business day.
  • Clear warranty & fitment support: details in Fitment & Use Policy below.
  • U.S. support: fitment help by chassis and engine code.

If it’s not a part we’d trust on our own M274, you won’t see it listed here.

Fitment & Use Policy

  • Guaranteed Fitment: verified for C300, GLC300, E300, and SLC300 with the M274 engine. If a part doesn’t fit, return it unused for a refund or exchange.
  • Off-Road Disclaimer: catless downpipes and certain performance parts are intended for off-road/competition use only. Buyer is responsible for emissions compliance.
  • CEL & Tuning: downpipes may trigger a CEL; an M274 ECU tune is recommended to prevent this and extract full performance.

Start with Downpipes for M274 — then add an ECU Tune and Braided Brake Lines for a complete, reliable package.