Update, being that most aftermarket UCA's are meant for 2.5"+ of lift / level I went ahead and ordered the MOOG premium UCA's, my stockers lasted 92k so....
While working on the front end I went ahead and got lower BG's, inner / outer tie rods for them to install.
I have the wheel bearings as well and with 92k and the front end already apart am debating having those installed as well.
By the time I am done I will have a mostly new front end given my Fox2.0 struts only have a few thousand miles on them.
Back to the spacers topic, how thick can you go and still use the factory studs?
I think that MikeBMW stated he did 1/2".
What have others done?