First time doing on a Mercedes was a bit challenging as we were discovering how to. No shocks no need
If you want the correct handling I would suggest you replace the shocks with the correct length ones for that lowering kit.
The springs basically just "set" the ride height, adding shortened shocks just means it will handle better as it doesnt have such a long travel that you would use with OEM springs.
Since many people just add shorter springs to lower their cars but leave the standard length shocks, it eventually kills the shocks and doesnt handle as well as it should over bumps and so on as its already depressed low compared to how it should sit when the car has stock springs which sit higher.
It then affects the cars lets call it "recoil" from the springs when you drive over a bump, it doesnt give the right pressure from the shocks to absorb the bumps smoothly as its close to bottoming out the shocks.
Also by having the shocks constantly compressed with the lowering kit, if they are old the rubber seals tend to start leaking due to the high pressure that it is constantly sitting under thus putting your life in danger and compromising looks for safety. You will end up having to replace the shocks as well which would have been easier to do in the first place while replacing the springs.