dont do it by slines mate, this is not good for your car, well its not supposed to be
some people have had it done and said its fine, but by doing it like this you could damage the bearings and seals and could lead to needing a rebuilt beam, or soo ive read
do it like the way in the guide theres a couple on here mate
try having a look at this guide
http://www.saxperience.com/forum/sho...=torsion+guide
doing it this way is by removing the bars themselves then lifting the arm to the desired hight and put bars back in its a bit harder, but this way you can lower by what ever drop you want, instead of a set drop like doing it by splines
hope this helps mate