For a long time, a lot of cars have had a multiplug in the boot. If you buy your kit from, or have it fitted by the dealer, their kit should plug in to the multiplug in the boot, no Scotchlocks or soldering required.I have always fitted my own, including the mechanical and the electrics, so I know it is done, and done properly. Many of the installers use scotch lock, insulation piercing connectors, t. o splice into the existing wiring. Trouble is, the slightest bit of moisture and the connector and wiring is rotted away to nothing. A proper, reliable job needs all connection to be soldered, and heat shrink sleeved.