From Andy Green's build thread:
Although I’d previously spent a few hours making the intermediate steering coupling, this has now been scrapped as I decided to fit electric power-steering unit.
The unit I’m using is off a 2001-06 Vauxhall Corsa (Corsa C) and an interface unit is readily available (from Ebay) to vary the amount of assistance the motor gives. Whether the car needs it I’m not sure, but it is easier to fit it at this stage than trying to get it in later.
For those of you worried about getting the car through the SVA test in relation to the collapsible section, the good news is that the Corsa column has an integral collapsible section. I’ve mounted mine to take advantage of this, the upper mount supports the collapsible section (although this may not be needed) and the 2 lower mounts, which are amore rigid support the main body. It’s also worth getting the intermediate column section, as this has a splined sleeve making it length adjustable and is then easily adapted to the Ford spline on the rack