Dropped my van around 40 mm at the back with a full camper conversion resulting in noticeably less roll and a more comfortable ride from the normal springs.
Also dropped down the torsion bars at the front to match.(youtube it)
Will need to let it settle for a few weeks and get 4 wheel wheel alignment done to check tracking and camber.
Great product- provides near OE ride quality. I had previously wasted my money on 2 sets of cheap lowering springs that both gave a very harsh ride- I wish I'd bought these in the first place!