I have a 2005 SL500 that someone took the original radio/ nav out of the car and replaced with some cheap unit . There are lots of radio's available for the SL500 but not with fiber optic amplifiers and the factory radio/ nav is $7000 . I am told by the dealer that the modules that are in the head of the radio gets info from the radio for things like ride hieght and other info the runs the cars electronics . I am looking for a reasonable alternative to fix this issue and i need some good advise