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RENNtech HHT-Hand Held Tuner | ECU Upgrade | R199 | SLR McLaren | 675 HP / 646 LB-FT | M155 | 5.5L V8 Supercharged

The RENNtech ECU Plus Upgrade brings the SLR McLaren up to 675 HP and 646 LB-FT | Gains: +47 HP and +25 LB-FT.
SKU: ECU-TU.54.199.SLR
Retail price without tax: $3,480.00

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RENNtech HHT (hand held tuner) allows you the unlimited ability to switch between tuned and stock ECU programming and requires no ECU removal!

Our 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.

The RENNtech tuning software for Mercedes offers significant gains in horsepower and torque across the vehicles entire power band. By modifying ignition timing and throttle mapping, optimizing air/ fuel ratios, increasing the engines rev limiter and modifying boost mapping for turbo charged vehicles, RENNtech performance software unleashes your Mercedes true potential.

RENNtech has been at the forefront of ECU tuning since electronic engine management started to show up in vehicles during the mid 1980's! Our experience, countless hours of in house research, development and exhaustive testing ensure that our proprietary ECU upgrade offers incredible performance gains and rock solid daily driver reliability.

With the RENNtech ECU Plus Upgrade the R199 - SLR McLaren gains up to +47 HP and +25 LB-FT, based on power numbers measured by RENNtech. Please note that the Mercedes M276 engine performance when measured, obtains higher numbers than rated from factory. The maximum power number reached with the RENNtech ECU Plus Upgrade for the R199 - SLR McLaren is up to 675 HP and 646 LB-FT.




  • Mercedes M155 engine performance when measured, obtains higher numbers than rated from factory.
  • Power gains are calculated with stock numbers measured by RENNtech
  • Crank Performance Numbers are calculated with a 17% Drivetrain loss.
  • Our numbers will be dependent on conditions and fuel quality. 93+ Octane gasoline is mandatory with this Performance Package.
  • Due to fuel quality problems, not all states can be supplied with the full power Upgrade. Please call for detailed info +1-561-845-7888.


Performance Numbers Overview 

SLR McLaren (R199 | M155 | 5.5L V8 Supercharged) Stock Performance:

  • Rated by Mercedes-Benz:        617 HP @ 6,500 RPM; 580 LB-FT @ 3,250-5,000 RPM
  • Rated by RENNtech:                628 HP @ 6,400 RPM; 621 LB-FT @ 4,050 RPM
    • Mercedes M155 engine performance when measured, obtains higher power numbers than rated from factory.


SLR McLaren (R199 | M155 | 5.5L V8 Supercharged) Modified Performance:

  • Rated by RENNtech:                675 HP @ 6,400 RPM; 646 LB-FT @ 3,200 RPM
    • Crank Performance Numbers are calculated with a 17% Drivetrain loss.


Dyno-Graph for Performance measured at the wheels:


Contact us

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


© 2017 RENNtech, Inc. All Rights Reserved.
7825 SW Ellipse Way - Stuart, FL 34997
TEL: 561.845.7888 FAX: 561.845.6777 E-MAIL: