You can cut the XR3i wiring loom about half way along the drivers side door as the RST Wiring is the same to the back lights etc. All colours match up on the RST side apart from one extra wire a black and white one (I think) which I taped up and and left disconnected. You need to replace the front end wiring by ripping the dash out and pulling the loom through the fuse box hole out into the engine bay. Any probs give me shout. Took me a day to replace the wiring easy job.

Cheers
Dave