Check this post re: 3mm spring pads.
http://www.bimmer.info/forum/showthr...23219#poststop
Cutting them is less elegant because the coil shape is not consistent, so you'd end up with the end of the spring not seated properly in the strut tower. Somewhat more dangerous - will it kill you? Don't know.
Maybe you just need to install some lead weights in the engine compartment?
HTH