Also not really regarded as *road safe*.
I'm surprised its having an effect on the driveshafts - as standard, the wishbones are like this (really exaggerated)
/ \
then after lowering about 40mm, they are like this
- -
then after lowering about 60-80mm they are like this,
\ /
If anything, I would have thought lowering 40mm would have the worst effect, considering the arc the driveshafts will move in. Lowered more than that - its likely to be like stock again.