update after installing the Sprint Booster.....Marvelous!!!...easy install...took me about a hour...you need to take the bottom panel out on the driver's side....then remove the gas peddle...unplug from the harness...the booster goes into the peddle plug then reattach to the harness....also has a remote button/cable....three settings, normal, green (more aggressive peddle), and red (quickest)....I absolutely love this device, I previously installed one on my E Coupe 350, totally transformed that car....in this case with the GLA it also totally transforms the peddle....now very quick, no lag, not "soft" anymore, and quite linear and progressive. I've tested all stages (green and red) and I prefer driving in E mode (without the stop/go function) with the booster in "Red"....very smooth shifting...in "Red" the throttle action is linear and immediate...no deed space anymore....in Sport or Manual, in "Red" the car launches quickly and aggressively....amazing...this device totally transformed the nature of the gas peddle and the quality of the shifting action....very quick and enjoyable.
(now in E mode, booster on "Red"...it shifts smoothly and quickly...quicker than in normal Sport mode)