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RENNtech ECU Upgrade | GL 550 | X166 | 480HP / 605LB-FT | 4.7L BiTurbo | M278 Engine

ECU Upgrade | 480HP / 605LB-FT | Gains: +32HP / +67LB-FT
SKU: ECU:54.166.GL550BI
Retail price without tax: $2,240.00

Our intermediate level ECU upgrade for the Mercedes M278 engine still offers huge gains in performance across the entire RPM range, but with a slightly reduced peak HP and torque from our standard tune.

This is ideal for customers who want increased performance in their daily driver without worry of extra strain on driveline components or for areas and countries with extreme altitudes, temperatures or fuel quality concerns. 

Our intermediate ECU tune increases performance from 429 HP and 516 lb/ft torque up to 480 HP and 605 lb/ft at the crank! This is a slight reduction from our standard tune but still offers white knuckle performance at one of the most affordable price points in the tuning market.




  • We have found the M278 engine stock performance numbers vary from the baseline figures claimed by Mercedes Benz. We typically see higher baseline numbers than claimed by the factory.
  • Power gains are calculated based on stock numbers measured by RENNtech. Crank Performance Numbers are calculated with a 18% Drivetrain loss on 4MATIC SUVs.
  • Our numbers will be dependent on conditions and fuel quality. 91+ Octane gasoline is mandatory with this Performance Upgrade.
  • States known for poor fuel quality have to be supplied with a lower power setup. Please call for details and Race fuel options +1-561-845-7888.



Performance Numbers Overview 


GL550 (W166 | MY2013-15 | 4MATIC | M278 | 4.7L V8 BiTurbo) Stock Performance (at crank):

  • Rated by Mercedes-Benz:      429 HP @ 5,500rpm; 516 LB-FT @ 2,000-4,500rpm
  • Rated by RENNtech:               448 HP @ 5,500rpm; 538LB-FT @2,800-3,900rpm
    • Note: Mercedes M278 engine performance when measured, obtains higher power numbers than rated from factory.



GL550 (W166 | MY2013-15 | 4MATIC | M278 | 4.7L V8 BiTurbo) Modified Performance (at crank):

  • Rated by RENNtech:               480 HP @ 5,500rpm; 605 LB-FT @ 3,700rpm
                                                    396awhp @ 5,500rpm; 496awtq @ 3,700rpm
    • Crank Performance Numbers are calculated with a 18% Drivetrain loss on 4MATIC SUVs.


Contact us

7825 SW Ellipse Way, Stuart, FL 34997
(+1) 561 - 845 7888
Mon - Fri 9am - 6pm


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7825 SW Ellipse Way - Stuart, FL 34997
TEL: 561.845.7888 FAX: 561.845.6777 E-MAIL: