Weird that your '91 has that setup? What options do you have? Sunroof? My '91 300E has a sunroof and came stock with 3 bump up front, 2 bump rear. When I changed my springs, I lowered both ends a bump (2 front, 1 rear) and am happy with the results.

Appparently it depends on the weight of the car when it comes off the assembly line with options factored in.

Good luck!

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi