I used the simple expedience of using a cut off wheel to trim 13 CM off the bottom end of the coils. I did some measurements with the wheel free from any springs, and confirmed to my satisfaction that there was plenty more drop available before things started bashing into one another. If I were to do it over, I would probably only cut 7 cm off, so it would fit more cleanly on the lower spring perch, but only do this after they are well and truly broken in. Wouldn't want them to settle unevenly. I will say that a lot of people would be shocked and upset at the notion of cutting springs, but done very conservatively its not a huge deal. There was no noticeable change in ride quality, and the change in handling was predictable as a result of changing the rake of the car.
Don't you mean mm instead of cm?
7mm is about 5/16 inch. 7cm is about 2-3/4 inches.
I have a hard time believing you cut almost 3 inches off a spring without major fitment issues.
That being said, I would like my car to be lower in the back so that the car sits almost level. I currently have DUB springs (Eibach Pro?). I was told that cutting the springs was a "bad idea (TM)".