Learned my lesson from trying this on the BX, when i rushed in and really loosened the clamp on the ARB and it took ages to get the height set right.
This time loosened it just enough so that it would move and tapped it gently with a hammer with the engine running and felt is lift slightly. Got the right height first time - bonus
Car seems to feel softer at the back and much more give when pushing down now. Added bonus is I am not being flashed at when on dipped beam anymore!