Hi Ryan48,
When I installed my shocks and springs I took down the part # off the rear spring pads (forgot to do so for the front). Anyway, I compared the part # with those posted on performance products (formerly automotion) for a 320slk. The #'s matched, I had the 5mm spring pads. 5mm is the thinnest pad offered. You might be able to shave a little, but at just 5mm if you shaved it I think the spring might cut through over time. Sorry I can't help with more info about the front spring pads.