Hi,
first of all - if you want to save some money please go with that kit:
Home Page > Search > 51710398336 > ES#127309 Fender Flare Retrofit Kit - 51710398336
It is genuine BMW and compatible with running boards. Front spoilers are never a problem because the arches do not touch the front bumper. Rear is also not a problem.
Another thread about this with pictures is here:
http://www.xoutpost.com/bmw-sav-foru...-arches-3.html
If you want to see how that arches looks at the end:
http://www.xoutpost.com/bmw-sav-foru...ore-after.html
Have fun
EDIT: if you have a car where the kit matches. Maybe you put some info into your profile.