I don't see many free stereo installs that are done right. I would be concerned on how they plan on wiring / re-wiring your car to work with the new radio. I see so many shops start on a 126 with amplifiers and then when they are @ 1 hour into it they come to you with bad news because the under estimated what needs to be done, or they take as many short cuts as they can to get you out of their shop. As I know your car I wouldn't let a shop that does free install experiment on your car. I would recommend you check with you local mbz dealer and ask who does all of their cars and see what they know before you go for the free install. I am of the belief that there is not many things in life that are free that are worth having ( other than the free doughnut at krispy kreme )

Scott

__________________
The Mercedes Specialists Since 1986