Leave the isolator alone.
See at the top of the spring. there are three coils that are very close together.
Chop one of those coils off.
You might need to take more, but removing that coil changes the rate of the whole spring, so its hard to guess exactly how much you need to take off. Too little is better than too much!
Thats what i did on the rear of my quattro. One spring was broken right at the end so i just rounded it up to a full coil and done the same on the other side.
I removed the insulator, AND hacked a part off the spring.
IIRC the top of the spring is pig tailed so lobbing a section off there may not be an option as it will no longer locate in the top mount.
Have you a pic of one of the old springs for comparison ?
I dont think you will get away with doing the front springs. I think the last coil on both ends is smaller.
Yes it is smaller but from what I understand you need to get rid of insulator to fit a bigger spring.
1999 Audi A4 1.8TQS - track car project
2007 Seat Altea 1.9Tdi