In so far as keeping MB parts on the car it's a combination of springs and pads del. However if you find the car is too high even on No 1 pads and short springs you can look to the red spring option that grober mentioned. For EACH PART NUMBER on the 124 springs there are TWO options, red or blue. Red is short blue is long. I put some reds in the back of the cabbie and almost need to go to a No 2 pad now, so they do make a difference.
You cannot order a red or blue spring, you can only order by part number. BUT the nice man at Irvine in California "found" a pair of reds for me.
You can also trim down the front spring if the spring pad combos aren't giving you what you want] 1/4 turn cut = approx 16 mm on a sportline spring. BUT be careful up front not to alter your ball point position beyond the range given as this is changed by lowering and alters your toe out on turns that can be felt be a very slight hesitant turn in and an immediate slight correction on the wheel when it does turn in. BPP is adjusted on the driver’s side using the splines on the output steering box shaft. Typically you run out of adjustment here.
The BPP measuring tool is very hard to find but it is a standard MB tool that techs should use when doing wheel alignments – they never do though!
Also make sure you have enough front camber adjustment to remove the excess –ve camber you tend to get when lowering. 1Deg 20 mins is about as deep as I want to go camber wise at the front otherwise you start getting into tyre wear issues.
At the rear you may find the camber gets over 2 Degrees which is when you want to start thinking about rear camber adjustment. Kmac do a spring link hole shifting bush, Speedway Motors in the US do an adjustable camber arm with forged ends not machined from bar stock. But probably the best solution is to plug the original camber arm with a pressfit solid bush into the Al boss and redrill the holes at 1.5 to 3.5 mm increased centres. You could also fit the adjustables, do the alignment at 1Deg 30 mins, remove the adjustables, measure the hole centres and drill the plugged originals at the new dimension, about 301 mm IIRC. That way you do not run the risk of nonstandard parts on a car that the Insurance co may be concerned with.
If you need to adjust the camber you will also need to adjust the rear toe which is adjustable from Factory, but again make sure you do not lower so much that you run out of rear toe adjustment.
AFAIK AMG and Braubus do not alter the rear camber because they use larger dia wheels which also fill the arches better and make the car appear to be lower.
I think a 1/2" drop on standard shocks will be fine, any more than that and you need to start thinking about shock stroke position and perhaps springs and shocks to match each other.
Bilstien do lowering kits, going this way I'd start with a small lowering to see how you like it...
Stock photo
Mine - as was...
Mine - as is...
