i lowered my 106 with 1.1 and VTR axles(same rear axle) a few times. could do it in a few hours in the end.
most fiddly bits are the 'wongy washers' on the end of th etorsion bars
also the torsion bars sieze in place so need ALOT of pursuasion with a big lump hammer and ideally a spare torsion bar, or some other knocking stick.
other awkward things are the brake bias valve system getting in your way.
theres a website called badger motorsport that have a guide on doing it.
way i used to do it (i think)
unbolt top end of the shocks and measure distance from bottom of arch to centre of hub on both sides. make a note of each measurement.
remove nuts holding ARB end plate.
bang end plate up out the way
remove drivers side 'rear' torx bolt and wongy wongy washer.
remove drivers side 'front' wongy washer (may have to jack trailing arm up to get better access, fiddly at the best of times)
remove passenger side 'front' wongy washer
put jack under passenger trailing arm to take the weight and not rip the brake pipes.
bang the 'front' torsion bar out from the drivers side - no need to remove it fully, just so its dislocated out of its splines.
this will allow you to manouver the trailing arm out the way to get to the passenger side 'rear' wongy washer, remove it.
support the weight of the drivers side trailing arm with jack/axle stands etc.
whack the 'rear' torsion bar out from the passenger side.
using a jack, lift the drivers side trailing arm. move it to the right position (measuring from the same points and removing the distance you want to lower it). hold it at this position and refit the torsion bar. they will only go in in one position due to the splines so you wil have to keep turning it, trying it at each spline., once its back in put the wongy washers back in and the torx bolts.
measure the passenger side to the new height, hold there, put the bar in, rotating it till it will fit.
put wongy washer and torx screw back in each end.
hammer arb end plate back downwards and put the securing nut back in.
my memory rules.. lol
i got quoted by some places as much as £300 if the torsion bars are seized!
got mine done by illusion motorsport in coventry (used to be on PGAC forum) for its first lowering. think it was 120 quid including front spring fitting too.