RennTech Performance Ecu Upgrade For For Mercedes-Benz X166 GLS 450 Biturbo

VENDOR: RennTech

SKU: 54.166.GLS450BT

All orders will include an AutoTalent window decal


RennTech HHT (hand held tuner) allows you the unlimited ability to switch between tuned and stock ECU programming and requires no ECU removal. RennTech proprietary tuning module stores both the RennTech tuned file and your vehicles stock file. The module plugs directly into the OBD2 port and delivers the file you choose directly to the ECU. Programming takes only a few minutes and the vehicle can be reflashed at any time as many times as you wish.

RennTech proprietary ECU upgrade for the Mercedes M276 engine offers huge gains in performance across the entire RPM range without sacrificing around town comfort or daily driver reliability. Our ECU tune offers the biggest performance gains on the market with our dyno results increasing performance from 362 HP and 384 lb/ft torque, up to an astonishing 402 HP and 454 lb/ft at the crank. This allows the M276 engine to run the quarter mile in an impressive time and dramatically improves 0-60 mph times.


  • Provides ability to switch between tuned and stock ECU programming
  • Providing comfort or daily driver reliability
  • Significant gains in horsepower
  • Increases the performance
  • Significant gains torque 
  • Gains: +40HP & +70TQ

Stock Performance:

  • 362 hp @ 5,500-6,000 RPM; 384 lb-ft @ 1,800-4,000 RPM

Modified Performance:

  • 402 hp @ 5,300 RPM; 454 lb-ft @ 3,200 RPM

Vehicle Fitment:    

  • 2016 Mercedes-Benz X166 GLS 450 Biturbo
  • 2017 Mercedes-Benz X166 GLS 450 Biturbo
  • 2018 Mercedes-Benz X166 GLS 450 Biturbo
  • 2019 Mercedes-Benz X166 GLS 450 Biturbo
  • 2020 Mercedes-Benz X166 GLS 450 Biturbo


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