onion: Yes, i had to buy the software package which came with various wiring diagrams, it's worth mentioning tho that none of them were specific to an rst so u need a fairly goood electrical knowledge to be fair. Basically the wiring harness i had to use was a universal one which i had to start from scratch....u basically get the multi pin plug that goes in the back of the ecu with all the wires coming out of the plug, they do various part assembled looms tho i believe.