nothing to do with shock absorbers, if you anywhere near 100mm ground clearance then you surely have lowered or cut springs and just need to get standard height ones

standard ground clearance of sill is well over 150mm something like 180mm

maybe measure from bottom of sill to ground (in front of the doors) and tell us the measurement

really without knowing what you have in there it's hard to help, but given the engineer has issues surely you had a seriously low setup to start with

the extra 20-30kg of a ca is only gonna drop the the car 5-10mm at a guess