ECU UPGRADE | HAND HELD TUNER | HHT | 550 | M278 - 4.7L V8 BITURBO
Overall, very impressed with my total RENNtech experience. Tune install was as advertised on my 2016 S550 Coupe. Shifts in both Comfort and Sport settings very smooth. Shifts seem to be better timed than stock as well. I haven’t pushed the car hard yet but you can feel the torque and power is ready for anything. Many that to Patrick at RENNtech for his support.