I don't see why you don't continue to post in your original thread:
850R Front suspension ?
A recent thread from Kevin0607 on same:
Bilstein B4 shocks
In my experience with B4's, albeit on an '03 S40 with Eibach Pro Kit springs, left a lot to be desired. Whatever you do don't go off the motorway with this combo! Serious feedback from all four corners so I immediately reverted back to original SACHS shocks and sold on the B4's. Honesty, it was like night and day!
Unfortunately, I can not offer experience on the B6's but my understanding is they are aimed at/for track use. Someone of more experience with B6 on a P80 will share soon hopefully.