Originally Posted by ajsalida
Have the same combo on my car. Lot of people are using OEM e36 M3 bump stops in front. I did and they work fine. Whatever you need them to be shorter than the OEM 335xi, and after 60k miles yours may just crumble into dust if you try to cut them. Rears need to be trimmed 1", some have used Z4 stops. I just trimmed the originals, off of the thicker firmer part leaving the progressive part. Also you may want new dust boots, or reuse the boots you've got. The bump stops fit into them and keep the shaft from getting too scratched or dirty & possibly contaminating seals.
Other than that no extra parts are needed, the hats were for people trying to use lowering perches which no one seems to be very pleased with on an Xi. If you are doing it yourself be sure to read the various DIY threads in the DIY section, and have all the right tools on hand, including a good spring compressor. It is not very hard but you can screw it up if you aren't careful. (Do not follow the one where the guy takes the springs off without taking the strut assembly out, I do not know what that guy was thinking.)
Make absolutely certain you get the strut housing seated as far down as they can go in the front hubs, many folks screw this up and wonder why their car isn't low enough. With the Konis they'll stick out a good 2" below the hubs.
Many recommend to set the struts 1/2 turn from full soft, full soft is only relative to full hard on these shocks, and full soft is a lot stiffer than stock.
edit: you'll love them, good luck.
Just got my Koni/Eibach installed with advice from ajsalida and others. The bumpstops and other notes were dead on. Thanks again for the help!