i've got BC V1 with 15" on mine
on my blog i receive and install em on page 12 post 558
http://www.micra.org.uk/threads/35251-PollyMobiles-Rebuild/page12
and corner balance em on page 32 post 1571
currently lowered 50mm front rear.
can lower much as ya want Mimz depending on if u can get a jack underneath but bare in mind lowering it alot means less available travel and may need a harder spring to prevent hittin the bumpstop which means a harsher ride.
at the lowest rear damper position, the rear hits the bumpstop when the rim is 67mm from the arch.
the front lower ring affects where the wheel stops when hitting the bumpstop. mines set so the rim is 60mm from the arch when it hits the bumpstop.
big difference between fully hard & fully soft damper settings. fully hard should prob just be used on smooth track although was hilarious on street roads but only for 5secs. at fully soft it was so much smoother on british roads. bout as soft as my previous bilstein streetline lowering kit.
ppl in the back do complain of a very bumpy ride over rough london roads, though the rear end also has no weight of the spare tyre etc to hold it down.
if the ride is too harsh, BC sells seperate softer springs