I currently have Bilstein PSS coils on my M5, but I had a well used and auto-xed Ground Control setup in my MCoupe. It should last as long as a regular set of Konis, in fact unless you blow the shock/strut or it begins to leak fluid profusely from the valve you should be OK. Since the Koni is adjustable you would also be able to compensate for wear by stiffening it up slightly as necessary, if you felt the car was getting "soft". The springs probably have a useful life in the hundreds of thousands of miles, and GC offers springs inexpensively so you can buy various rates for only a couple hundred dollars.
Frankly I wouldn't worry about the suspension, but likely the mounts, bushings and arms will need a refresh before the suspension itself does.
Out of curiosity does the GC setup for the M5 creak and moan over bumps? With the MZ3 system, its well documented it creaks and moans like an old man getting out of a La-Z-Boy.
Frankly I wouldn't worry about the suspension, but likely the mounts, bushings and arms will need a refresh before the suspension itself does.
Out of curiosity does the GC setup for the M5 creak and moan over bumps? With the MZ3 system, its well documented it creaks and moans like an old man getting out of a La-Z-Boy.