Yes I know that options will influence the weight thus the spring rate.
Normally for one type of car, lets say the E90 + E92 M3 the letter should be the same, but the number changes.
For light (no options) E92 m3 it is front X1 rear X1 or X2
As posted a full option M3 E92 has X4 up to X7
What makes me strange is that the springs I got from ebay from en E90 M3 have the marking Y4 in front and Y2 in rear.
Changing from X to Y letter, the thickness is 1mm extra for the Y !! This makes the springs a lot more stiff, no sense for an E90!?
Maybe the ebay dude has taken the springs from an E93 M3? and don't want to admit it? But the shocks that where bundled with these springs are indeed from E90 M3 (checked on realoem.com)
Any marking for E93 please?